The invention provides a method for synthesizing spiropyran polymers, which is characterized by comprising the following steps: 1, weighing and dissolving polyacrylic acid monomers and initiators; 2, performing polymerization; 3, cleaning precipitate and performing drying treatment to obtain random polymers; 4, preparing spiropyran compounds according to documents; 5, calculating the amount of spiropyran, dicyclohexyl carbon bisimide serving as an esterification catalyst, as well as p-lutidine put in; 6, dissolving the obtained product in DMF and performing reaction for 24 hours at room temperature away from light; and 7, entering a precipitation process and obtaining the spiropyran polymers. The method has the advantage of improving the stability of colored structure, namely prolonging photochromic cycle bymodifying spiropyran molecules and connecting the spiropyran molecules with acrylate macromolecules. By regulating the composition of a polymer matrix and the content of active groups, the method obtains the polymers with different spiropyran content, namely the polymers with different chromotropic intensity, thereby expanding the application of the product in paint and plastics industries.