In recent years, organic-inorganic hybrid perovskite solar cells have received a lot of attention for their excellent performance and low manufacturing cost. However, the toxicity of lead in organic-inorganic hybrid perovskite solar cells and instability inhibits its further commercialization. Double perovskite Cs₂AgBiBr₆ possess excellent stability, low toxicity, long carrier lifetime, and small effective carrier mass, and is considered as a promising photovoltaic material. It has been applied in solar cells and displayed superior performance. However, the power conversion efficiency of Cs₂AgBiBr₆ perovskite solar cell still lags behind organic-inorganic hybrid perovskite solar cells, and its development faces various challenges. This review firstly introduces the crystal structure and the structural parameters such as tolerance factor of Cs₂AgBiBr₆. And then, the progress of thin film preparation technologies such as solution processing method, anti-solvent assisted film forming method, vapor deposition processing method, vacuum-assisted film forming method, spray-coating method are summarized, and the advantages and disadvantages of various preparation technologies are discussed. The performance optimization strategies of Cs₂AgBiBr₆ perovskite solar cells are analyzed from three aspects: element doping, additive engineering, and interface engineering (interface energy level matching and interface defect passivation), and the research progress in recent years is reviewed. Finally, the challenges faced by Cs₂AgBiBr₆ perovskite solar cells are pointed out, and future research directions are prospected from three aspects: precursor solvent engineering, bandgap engineering, and device degradation mechanism.