Investigations reveal thymidine phosphorylase has the effects of promoting tumor angiogenesis and inhibiting cell apoptosis, and is closely related to the prognosis and outcome of the cancer patients. Meanwhile, it is also the key converting enzyme for the prodrugs of 5-fluorouracil such as 5'-deoxy-5-fluorouridine. This paper reviews the advances in the investigation of thymidine phosphorylase, including its expression and function in colorectal cancer tissue, converting effect on 5'-deoxy-5-fluorouridine and therapeutic potential.