The present invention relates to crystalline forms of mesaconine. Specifically, the present invention relates to crystalline form A, crystalline form B, and crystalline form C of mesaconine and a preparation method therefor. The method comprises: performing crystallization on mesaconine in a solvent, and performing drying to obtain a target crystalline form. The crystalline forms of mesaconine in the present invention have good solubility, good stability, low hygroscopicity, and good repeatability, and are suitable for long-term storage and drug development.