This study will focus on postoperative patients of stage IIIB or stage IIIC colorectal cancer. These patients will start to accept chemotherapy in 3-4 weeks after operation, these patients were randomly divided into two groups, one group will accept adjuvant chemotherapy of mFOLFOX6; another group will use mFOLFOX6 combined with apatinib. The efficacy and safety of adjuvant chemotherapy will be compared between the two groups. Disease-free survival, overall survival, incidence of adverse reaction of chemotherapy and postoperative quality of life will be recorded.

Inclusion Criteria:

1. signed informed consent form;
2. confirmed as colorectal cancer by pathology, and the stage is IIIB /IIIC according to the NCCN guidelines;
3. patients with primary colorectal cancer;
4. radical resection of colon cancer (CME) or radical resection of rectal cancer (TME) has done;
5. 3~4 weeks after radical resection ;
6. patients did not receive any radiotherapy and chemotherapy before operation

Exclusion Criteria:

1. emergency operation for colorectal cancer patients;
2. the situation after operation can not tolerance for systemic adjuvant chemotherapy (hemoglobin <95g/L, white blood cell <3 * 109/L, granulocyte <1.5 * 109/L and platelet <75 * 109/L, bilirubin>2.5N, alanine aminotransferase >2.5N, alkaline phosphatase >2.5N, urea nitrogen >2.5N, creatinine >2.5N, proteinuria, hematuria, temperature of >38 degree);
3. serious diseases such as cardiac insufficiency, respiratory insufficiency, liver and kidney dysfunction, serious blood diseases;
4. patients participated in other clinical trials at the same time;
5. pregnant or perinatal women;
6. combined with other malignant tumors;
7. a history of neuropsychiatric disorders;
8. patients have used anti angiogenesis targeted drugs (such as bevacizumab, cetuximab);
9. patients had a history of severe trauma within 4 weeks before admission;
10. allergic to chemotherapy drugs or apatinib;
11. active bleeding, ulcers, intestinal perforation, intestinal obstruction, hypertension

our study protocol,statistical analysis plan,informed consent form and clinical study report are Chinese.