Above all, so far, there is no data to demonstrate that regular 4-6 month chemotherapy followed by maintaining treatment could prolong TTP and OS for advanced colorectal cancer. Capecitabine is effective for colorectal cancer, and was approved as palliative treatment for advanced colorectal cancer and adjuvant chemotherapy; in addition, with its relative less frequency of side effects and convenient oral administration, capecitabine as maintaining regimen could be prone to be accepted by patients. Therefore, our study is designed to investigate that capecitabine as maintaining treatment after first-line palliative chemotherapy could improve TTP and OS for patients with advanced colorectal cancer through a perspective randomized clinical study.