Disclosed are new crystal forms of dapagliflozin and a preparation method thereof. Particularly, the X-ray powder diffraction pattern of the crystal form A of dapagliflozin has characteristic diffraction peaks at the following 2θ angles: 6.3±0.2°, 12.5±0.2°, 16.0±0.2°, 18.8±0.2°, 26.4±0.2°, and 27.1±0.2°. The X-ray powder diffraction pattern of the crystal form B of dapagliflozin has characteristic diffraction peaks at the following 2θ angles: 6.3±0.2°, 7.2±0.2°, 14.5±0.2°, 19.6±0.2°, 21.3±0.2°, and 23.6±0.2°. The crystal form A is hemi-ethanol solvate, which is stable when it is baked at 10-30℃. The ethanol solvent can be easily removed by baking at 45-55℃ to obtain the anhydrous crystal form B. The crystal form A is an intermediate state crystal form of the anhydrous crystal form B. At the same time, the crystal form A of hemi-ethanol solvate can be directly used in preparation by performing wet granulation and removing the solvent by baking, and can meet the quality requirements of the preparation. The crystal form B has a low water content, a high purity, a good product stability at 60℃ high temperature, a simple preparation process with mild operation conditions, and is suitable for large scale industrial production.L'invention concerne de nouvelles formes cristallines de dapagliflozine et un procédé de préparation associé. En particulier, le motif de diffraction de rayons X sur poudre de la forme cristalline A de dapagliflozine a des pics de diffraction caractéristiques aux angles 2θ suivants : 6,3 ± 0,2°, 12,5 ± 0,2°, 16,0 ± 0,2°, 18,8 ± 0,2°, 26,4 ± 0,2° et 27,1 ± 0,2°. Le motif de diffraction de rayons X sur poudre de la forme cristalline B de dapagliflozine a des pics de diffraction caractéristiques aux angles 2θ suivants : 6,3 ± 0,2°, 7,2 ± 0,2°, 14,5 ± 0,2°, 19,6 ± 0,2°, 21,3 ± 0,2° et 23,6 ± 0,2°. La forme cristalline A est un solvate hémi-éthanolique, qui est stable lorsqu'il est cuit à 10-30 °C. Le solvant éthanolique peut être facilement éliminé par
