The present invention relates to Form crystal of bisulfate of janus kinase (JAK) inhibitor and preparation method thereof. Specifically, The present invention relates to Form II crystal of (3aR,5s,6aS)-N-(3-methoxyl-1,2,4-thiadiazole-5-group)-5-(methyl(7H-pyrrolo[2,3-d]pyrimidine-4-group)amino)hexahydrocyclopenta[c]pyrrole-2(1H)-formamide bisulfate and a preparation method thereof. The said method comprises crystallizing any crystalline or amorphous of compound solid of formula (I) in the single or mixture of organic solvent to obtain Form II crystal. The Form II crystal of compound of formula (I) has good chemical stability and crystal stability, low toxicity and low residue of crystallization solvent, can be better used for clinical treatment.本發明涉及一種JAK激酶抑制劑的硫酸氫鹽的結晶形式及其製備方法。具體地，本發明涉及(3aR,5s,6aS)-N-(3-甲氧基-1,2,4-噻二唑-5-基)-5-(甲基(7H-吡咯并[2,3-d]嘧啶-4-基)胺基)六氫環戊并[c]吡咯-2(1H)-甲醯胺硫酸氫鹽的II型結晶及其製備方法。所述製備方法包括將任何晶型或無定型的式(I)化合物固體在單一的有機溶劑或者它們的混合有機溶劑中結晶得到式(I)化合物的II型結晶。本發明所得到式(I)化合物的II型結晶具備良好的晶型安定性和化學安定性，並且所用結晶溶劑低毒低殘留，可更好地用於臨床治療。
