Patients with stage II colorectal cancer should be confirmed to have the following five high-risk factors: poor histological differentiation (grade III or IV), T4, vascular lymphovascular infiltration, preoperative intestinal obstruction or intestinal perforation, and insufficient lymph nodes detected in the specimen (<12). ①Stage II colorectal cancer without high-risk factors is recommended for follow-up observation or chemotherapy with single-agent fluorouracil-based drugs. ②For stage II colorectal cancer with high-risk factors, adjuvant chemotherapy is recommended. The chemotherapy regimen recommended is 5-FU/LV, capecitabine, 5-FU/LV/oxaliplatin or CapeOx regimen. (iii) It is recommended to test tissue specimens for MMR or microsatellite instability (MSI) if available. In case of mismatch repair defect (dMMR) or microsatellite instability (MSI-H), single-agent adjuvant chemotherapy with fluorouracil-based drugs is not recommended.