Abstract: Carotenoids are the most common lipid-soluble plant pigments in nature, which have the functions of antioxidation and prevention of many diseases. In general, most natural carotenoids exist in an all trans configuration, with low biological activity and bioavailability. Cis-isomerization of carotenoids is an important means to improve its application value. On the basis of expounding the isomerization reaction mechanism, this paper reviews the isomerization methods (thermo-isomerization, thermally induced catalytic isomerization, photoisomerization, etc.), factors affecting isomerization reaction, and the effect of isomerization on its biological activity and bioavailability under different evaluation methods. Finally, the problems in the process of carotenoid isomerization and future research directions are proposed.