The invention provides a method for synthesizing and optimizing a kinoform, wherein the method is based on a genetic algorithm. The technical scheme provided by the invention comprises the following steps: adding a group of random phase masks to original images; optimizing the masks; and when reaching optimizing conditions,taking the phase mask with minimum cost function as the best mask, and thecorresponding kinoform of the best mask as the obtained kinoform. The Kinoforms are indirectly optimized by optimizing the masks. Ihe method, the error of reproduced images is reduced by directly optimizing the random phase masks so as to optimize the Kinoform. In the selection link of the genetic algorithm, an elite retaining method is used to retain excellent solutions of groups and to accelerate the convergence rate, and is easy for realizing. Compared with the traditional optimization method, the method provided by the invention has the advantages of small initial cost function, fast optimizing speed, good optimizing effect and the like.