Abstract: The occurrence rate of colorectal cancer is increasing. Metastasis and recurrence are the leading causes of death in colorectal cancer. Tumor cells in the circulation have the ability to proliferate or to migrate, thereby providing a reliable means for neoplasm staging and assessment of recurrence or metastasis, and evaluation of efficacy by detecting circulating tumor cells (CTC). Optimizing the development of detection technology will provide better support for clinical applications. This review mainly discusses CTC detection and advances in colorectal cancer relapse or metastasis.