The present disclosure relates to novel crystalline form I, form II and form III of 6-(1H-indazol-6-yl)-N-[4-(4-morpholinyl)phenyl]imidazo [1,2-a]pyrazin-8-amine mesylate, and preparation methods and use thereof. Crystalline form I is a dimesylate, and its X-ray powder diffraction pattern shows characteristic peaks at 2theta values of 5.9°±0.2°, 13.5°±0.2° and 21.8°±0.2°. Crystalline form II is a dimesylate, and its X-ray powder diffraction pattern shows characteristic peaks at 2theta values of 15.8°±±0.2°, 17.2°±0.2° and 19.5°±0.2°. Crystalline form III is a monomesylate, and its X-ray powder diffraction pattern shows characteristic peaks at 2theta values of 7.4°±0.2°, 12.9°±0.2° and 19.2°±0.2°. The crystalline forms are more suitable for drug development than prior crystalline forms, and the preparation methods for the crystalline forms are simple and repeatable and have significant value for future drug optimization and development.
