The present invention relates to a
crystal form of
Ribociclib monosuccinate, whose X-
ray powder diffraction pattern at 25°C has a 2theta value of 9.0°±0.2°, 9.5°±0.2°, 11.5±0.2°, 12.9±0.2°, 13.9±0.2°, 15.1±0.2°, 15.8±0.2°, 17.7±0.2°, 18.3±0.2°, 19.0±0.2°, 20.5±0.2°, 21.9±0.2°, 23.0±0.2°, 23.9±0.2°, 24.9±0.2°, 25.9±0.2°, 27.9±0.2°, 29.2±0.2°, 29.9±0.2°, 30.5±0.2°, 32.0±0.2°, 33.7±0.2°, 36.2±0.2°, There are characteristic peaks at 37.4±0.2°, 37.7±0.2°, 39.5±0.2°, 41.0±0.2°, 41.6±0.2°, 44.0±0.2°. The
crystal form I provided by the invention has low hygroscopicity, simplifies the preparation and post-treatment process of medicines, and is easy for industrial production. Compared with the existing
crystal forms, the crystal form I has better stability, and it is not easy to turn crystals during storage, so as to avoid changes in
bioavailability and
drug efficacy. At the same time, it has better
powder properties and has a strong Economic Value.