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 I 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 organic solvent to obtain Form I crystal. The Form I 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I型結晶及其製備方法。所述製備方法包括將任意晶型或無定型的式(I)化合物固體在單一的有機溶劑中結晶得到I型結晶。本發明所得到式(I)化合物的I型結晶具備良好的晶型穩定性和化學穩定性，並且所用結晶溶劑低毒低殘留，可更好地用於臨床治療。
