A plurality of new crystal Forms I, II, III, IV, V, VI, VII, VIII, IX, X, XI, XII and XIV of 6-Acetyl-8-cyclopentyl-5-methyl-2-(5-piperazin-1-yl-pyridin-2-ylamino)-8H-pyrido[2, 3-d]pyrimidin-7-one, as well as a preparation method and medicinal use therefor are disclosed in the present disclosure. Crystal Form VIII is a semi-hydrate crystal Form. Compared to crystal Forms of the prior art, these new crystal Forms are markedly superior in respect of dissolution, stability, and the preparation process.