The present disclosure relates to crystal form A of 5-((4-ethylpiperazin-1-yl)methyl)-N-(5-fluoro-4-(4-fluoro-1-isopropyl-2-methyl-1H-benzo[d]imidazol-6-yl)pyridin-2-yl)pyrimidin-2-amine. The crystal form has a high purity, less residual solvent, high solubility and good stability; has good properties, fluidity and compressibility, and is convenient for production, detection, preparation of formulations, transportation and storage. The preparation method is easy to operate and is suitable for industrial production, and the crystal form can be used for treating and/or preventing diseases associated with CDK4/6 kinase-mediated cancers.