The treatment of stage II colon cancer is currently a hot and difficult research area worldwide. The DFS benefit of high-risk stage II chemotherapy is equivalent to that of stage III, and the MOSAIC trial confirmed that high-risk stage II colon cancer can benefit DFS from oxaliplatin adjuvant chemotherapy. the ACCENT trial confirmed that MMR deficiency (dMMr) is a good predictor of prognosis in untreated colon cancer. dMMR predicts the efficacy of FU-based adjuvant chemotherapy, and patients with dMMR do not benefit from 5 -FU single-agent chemotherapy. Therefore, stage II patients to be treated with 5-FU/LV or capecitabine monotherapy should be tested for MMR, and if they fall into the category of dMMR, they should not be given the above treatment. In contrast, dMMR can benefit from oxaliplatin-containing regimens.