The proposed study is a randomized, double-blind, placebo-controlled, multi-center Phase II study to investigate the safety and efficacy of SHR0302 in patients with moderate to severe active Crohn's Disease. The study aims to evaluate the optimal dose of SHR0302 and time needed in inducing clinical remission in active CD. This is an 12+12 weeks study, in which participants who complete the first 12 weeks treatment phase, will have the option to enter a blinded active arms 12-week extension phase. Early withdrawn subjects during the first treatment phase cannot enter the extension phase. The total duration of the study participation, including extension and follow-up, will be approximately 26 weeks.

With the wealth of scientific evidence on JAK/STAT involvement in IBD, the data from similar class of new drugs and the current data on SHR0302 (JAK1 inhibitor), support the rationale to proceed with phase II studies to evaluate the efficacy and safety of SHR0302 in patients with moderate to severe active CD.

Inclusion Criteria:

• Male and Female subject at ≥18 and ≤ 75 years of age at randomization.
• Subjects with a documented three-month history of diagnosed ileal, colonic, or ileocolonic Crohn's Disease at the time of randomization.
• Currently having Crohn's Disease with Crohn's Disease Activity Index (CDAI) score ≥ 220 to ≤450.

Exclusion Criteria:

• Diagnosis of indeterminate colitis, or clinical findings suggestive of Ulcerative Colitis.
• Subject with CD with stoma, gastric or ileoanal pouch, proto-colectomy or total colectomy, symptomatic stenosis or stricture, history of bowel perforation, suspected abscess; actively draining fistula.
• Treatment naïve subjects diagnosed with Crohn's disease, (without previous exposure to treatment).