In this study, a number of biological experiments in vitro had confirmed that C5aR1 knockdown inhibited the proliferation, colony formation, migration and invasion ability of CRC cells in vitro, while overexpression can obtain the opposite result, suggesting that C5aR1 plays a promoting role in the development of colorectal cancer and may be the oncogene of colorectal cancer. This evidence concerns the gene C5AR1 and colorectal carcinoma.