The solid oxide fuel cell (SOFC) is a crucial solution for addressing global energy and environmental challenges, due to its high energy conversion efficiency and environmental friendliness. The electrolyte is a key component of SOFC as it determines the operating temperature and output performance.This review introduced the mechanism and influencing factors governing the electrical conduction of zirconia-based electrolyte. The electrical conduction of zirconia-based electrolyte originates from the diffusion of oxygen ions and vacancies, thereby depending on their intrinsic properties, (i.e., crystal structure, dopant cation, film thickness and grain size), and on operating conditions, (i.e., temperature, oxygen partial pressure, and time).To promote the commercialization of SOFC, electrolytes should maintain a low ohmic resistance at a lower operating temperature. One effective approach is to reduce the thickness of the electrolyte while maintaining a dense microstructure. However, achieving simultaneous reduction in thickness and enhancement in density often has challenges. The fabrication methods of electrolytes mainly consist of three processes, i.e., precursor preparation, thin film formation and heat treatment. This review represented common fabrication methods employed for zirconia-based electrolyte thin films from the perspective of solid phase powder forming, liquid phase forming and vapor phase forming methods.For solid phase powder forming methods, the precursor can be either ceramic slurry or ceramic powder. These methods are often simple with short forming time. Tape casting, screen printing, and electrophoretic deposition are representative slurry-based techniques that are used in industrial production. Tape casting enables the production of dense films with a wide range of thicknesses, allowing the prepared films to serve as supported or non-supported layers. However, conventional tape casting technology utilizes organic solvents that have environmental concerns. Thus, an environmental-friendly aqueous-based tape casting technology is developed. Nevertheless, there is still room for improvement in terms of slurry stability and film mechanical properties. For screen printing, the microstructure of the film can be adjusted via regulating the slurry components, but it is difficult to eliminate defects like holes and cracks. Surface modification can be used as an effective way to reduce defects. For electrophoretic deposition, electrolyte films can be deposited on various conductive substrates with a few restrictions on their shapes. Removable conductive coatings can be employed to facilitate the film deposition on non-conductive substrates. In addition, slurry spin coating also enables to fabricate dense electrolytes with thickness as low as two micrometers. For slurry 3D printing technology, electrolytes with a sophisticated structures can be fabricated to increase the effective contact area between the electrolyte and the electrode. Besides, dry pressing method is commonly utilized for fabricating supported electrolyte layers., Dense films with a thickness down to ten micrometers can be realized via reducing the bulk density of powder.Liquid phase forming methods mainly contain sol-gel and spraying technologies. For sol-gel technology, even though dense thin films can be easily obtained, the long preparation time and high cost retard its commercialization. For spraying technology, it offers advantages like high deposition rate and a few restrictions on substrate shapes and sizes. However, the electrolyte films prepared by conventional spraying methods exhibit a high porosity, resulting in a poor electrochemical performance. To address this issue, novel techniques, such as vacuum plasma spraying and electrostatic spray deposition, and post-treatments, such as solution impregnation, are developed.Gas phase forming methods can be categorized into physical vapor deposition and chemical vapor deposition based on the deposition mechanism. The main feature of these methods lies in the capability to fabricate dense electrolyte thin films with submicron-sized thickness at low deposition temperatures. Magnetron sputtering is a typical physical vapor deposition method, characterized by producing dense films with a good uniformity. However, the fabricated thin films often exhibit columnar microstructures with pinholes. Such microstructures can be improved through substrate modification, bias voltage application, post-treatments, etc.. Pulsed laser deposition as a representative physical vapor deposition method allows the precise control of the stoichiometric ratio in films. High-quality multilayer electrolyte thin films and interfaces can be prepared by this technology, leading to superior output performance. For chemical vapor deposition, it can fabricate uniform dense thin films in a wide range of substrates. Conventional technology may generate corrosive products, hindering its further applications. To solve this problem, various technologies such as metal-organic chemical vapor deposition and atomic layer deposition are developed. These techniques also enable to prepare dense films with 100-nm thickness, effectively reducing the ohmic resistance and thus enhancing the performance of SOFC at lower temperatures.Summary and prospects In general, the electrolyte preparation methods discussed can be categorized into two aspects. The first aspect refers to methods for high performance. The as-fabricated films exhibit a high quality (i.e., thin, dense, and uniform), and their microstructures can be highly adjustable. Typical methods include magnetron sputtering, pulsed laser deposition, and chemical vapor deposition. However, these methods are often featured by high cost and difficulty in large area preparation. The second aspect refers to methods for large scale industrial production, which features simple process, high robustness, low cost, and suitability for large area preparation. Representative approaches are tape casting, screen printing, spraying, etc.. However, the electrochemical performance of the as-fabricated electrolyte still needs to be improved.It is important to further elucidate the structure-property relationships for SOFC electrolytes through fine processing and characterizing methods. The structure factors that should be considered include compositions, phase structures, microstructures, mesostructures, and interfaces. Also, it is essential to develop large-scale, low-cost, and robust preparation methods, and explore the influencing factors of performance in actual service conditions. Synergistic collaboration between these aspects is conducive to further enhancement of electrochemical performance while holding cost. In addition, the development of SOFC electrolyte preparing methods is a systematic engineering, necessitating consideration of adaptability to other components and practical application scenarios. The pursuit of these development directions will contribute to the commercialization of SOFC, thereby facilitating the realization of ‘carbon neutrality’ target.