A polycrystalline form of a dehydrophenylahistin-like compound, and a manufacturing and purification method and application thereof. A (3,6)-3-benzylidene-6-[(5--butyl-1-imidazol-4-yl)deuteromethylene]piperazine-2,5-dione monohydrate crystal and a (3,6)-3-benzylidene-6-[(5--butyl-1-imidazol-4-yl)methylene]piperazine-2,5-dion e monohydrate crystal are more competitive crystalline forms with stable quality. The manufacturing and purification method is simple and easy to operate, and can effectively control the generation of acontaminant to obtain a high purity product. The polycrystalline form of the dehydrophenylahistin-like compound has a certain value in an application for manufacturing an antitumor pharmaceutical product.
