The present invention relates to isethionate and crystalline form of cyclin-dependent kinase inhibitor and preparation methods thereof. Specifically, The present invention relates to 6-acetyl-8-cyclopentyl-5-methyl-2-((5-(piperidin-4-yl)pyridin-2-yl)amino)pyrido[2,3-d]pyrimidin-7( 8H)-one 2-hydroxyethanesulfonate (formula (I)) and form I crystal and preparation methods thereof. The form I crystal in this invention has good polymorph stability and chemical stability, furthermore, the solvent used for crystallization is low toxicity and low residual, so it can be better used for clinical treatment.本發明涉及一種週期素依賴性蛋白激酶抑制劑的羥乙基磺酸鹽、其結晶形式及製備方法。具體地，本發明涉及6-乙醯基-8-環戊基-5-甲基-2-((5-(哌啶-4-基)吡啶-2-基)胺基)吡啶並[2,3-d]嘧啶-7(8H)-酮羥乙基磺酸鹽(式(I)化合物)，其I型結晶及其製備方法。本發明所得到式(I)化合物的I型結晶具備良好的化學穩定性和晶型穩定性，並且所用結晶溶劑低毒低殘留，可更好地用於臨床治療。
