The focusing methods of solar concentrators are mainly classified into three categories. This study introduces the structural designs and operating principles of various solar concentrators, analyses their focusing performance, and summaries the latest research status at home and abroad. First, we consider a refractive concentrator, which involves the usage of Fresnel lens with varying shapes as the main optical element and exhibits a high design freedom, but the lens is sensitive to the spectrum and easy to produce dispersion. Second, we consider a reflective concentrator, which exhibits a simple structure, has natural advantages with respect to the solar spectrum, and covers a larger area, but its concentration ratio is generally low and its concentration efficiency is related to the refractive index of the coating on the reflector and other factors. Finally, we consider a hybrid concentrator, which can be obtained by combining concentrators under different operating principles to achieve maximum utilization of the solar energy and generate a uniform spot at the exit. With respect to the hybrid concentrator, the planar concentrator has attracted increasing attention because of its dynamic concentration ratio and high concentration efficiency; however, the manufacturing and coupling errors associated with the planar concentrator still need to be considered. Regardless, the solar concentrator is one of the key components of a concentrating photovoltaic system, and its research demonstrates considerable futuristic applications. From the development perspective, the optical concentrator designs exhibit considerable potentials because of their high efficiency, uniformity with respect to the focusing spot on the receiving surface, and advanced compact system structure. With the continuous development of the processing technology, the concentrator will become increasingly efficient and lightweight, thereby reducing its cost.