The industrialization of copper indium gallium selenide (Cu(In,Ga)Se₂, CIGS) solar cells has attracted worldwide attention. As a thin film solar cell with high conversion efficiency, its efficiency can be compared with that of crystalline silicon solar cell, and the highest efficiency reaches 23.35% at present. For small-area laboratory solar cells, the main research focus is to accurately control the stoichiometric ratio and efficiency of absorption layer. For industrial production, besides stoichiometric ratio and efficiency, cost, reproducibility, output and process compatibility are very important in commercial production. The research progress of different preparation processes, gradient control of absorption layer composition, post-deposition treatment of alkali metal, wide band gap cadmium-free buffer layer, transparent conductive layer and flexible substrate were reviewed. From the perspective of the efficiency of CIGS solar cells, the transfer of record-breaking high-efficiency solar cell technology in the laboratory to the average industrial production level brings obvious challenges.