Efficacy Study of T2 Versus AZA to Maintain Clinical and Endoscopic Remission in Postoperative Crohn's Disease

Inclusion Criteria: * Subjects should have a definitive diagnosis of Crohn's disease, based on WHO criteria * Subjects having curative resection/ileocolonic anastomosis，pathologically diagnosed as Crohn's disease * Lesions located in ileum or ileocecal region * Males and females ≥ 18 years old, including women who are not pregnant or lactating at the time of enrollment. * Body weight between 40 and 100 kg, inclusive. * Subjects should have a CDAI score \<150 at week 0 * Able to swallow tablets * Are capable of providing written informed consent and obtained at the time of enrollment * Willing to adhere to the study visit schedule and other protocol requirements. Exclusion Criteria: * Bacterial,viral or other microbial infection(including HIV) * any of the following medications taken within 12 weeks before surgery: cyclosporine, tacrolimus, sirolimus, mycophenolate mofetil, or other investigational drugs * any of ongoing therapy for Crohn's disease with: 5-ASA compounds, steroids, immune modifiers, systemic antibiotics, and tube feeding * Needing orally administered corticosteroids for the treatment of other diseases. Inhaled or dermatologic preparations are acceptable. * Previous or current use of infliximab. * current use of prescription doses or chronic/frequent use of NSAIDs * Treatment with narcotic pain medications. (Anti-diarrheal agents such as loperamide and diphenoxylate are permitted, providing that the dose is not increased during the study period.) * With an ileal or colonic stoma. * History of pancreatitis, except for subjects with a known but removed cause(such as gallstone pancreatitis) * WBC \<3.0 x 109/L, hemoglobin \<80 g/L, Platelets\<50,000/mm3 at the time of enrollment (or within the previous 6 months, if known) * History of abnormal liver function tests, including AST or ALT \>1.5 times upper limit of normal, alkaline phosphatase \>2 times upper limit of normal, total bilirubin \>2.5 mg/dL at screening (or within the previous 6 months, if known) * With short bowel syndrome (defined as requiring oral or parenteral supplemental or total nutrition to maintain stable body weight, or more than 100 cm of small bowel resected) * History of malignancy * Women who are pregnant or lactating at the time of enrollment, or who intend to be during the study period. * Participation in other clinical trial within the past 6 months