Abstract: In this paper, three methods, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and X-ray powder diffraction (PXRD), were used to characterize the structure of Palbociclib. The form-B crystal mixed in with form-A crystal, the effective form of Palbociclib, was quantitated by the single peak method (peak area method and peak height method) using X-ray powder diffraction. While the qualitative identification by DSC was not clear, SEM and PXRD quickly and effectively identified two types of crystal. The standard curve equations established by the peak area method and the peak height method are:y=0.842 75x-0.001 21 and y=0.909 64x-0.002 32. This suggests that the linear relationship of peak area method is better than that of peak height method (R²=0.986 17 and R²=0.985 83). The sensitivity of the peak area method (LOD=1.17%, LOQ=3.92%) are higher than the peak height method (LOD=1.19%, LOQ=3.97%). The methods from this study can be used to identify and quantify palbociclib form-A and form-B crystal rapidly.