AFP is clinically referred to as alpha-fetoprotein, which is a tumor marker and a glycoprotein with many physiological functions, including transport, immunity, induction of apoptosis, and growth regulation. Since the peripheral serum level is extremely low in adults, when alpha-fetoprotein is significantly elevated, it is mostly indicative of an abnormal state of the organism. Clinically, it is mainly used in the diagnosis of primary liver cancer, and is a relatively specific serum marker, which can also be used in the postoperative monitoring and follow-up of primary liver cancer. Not only primary liver cancer can cause elevated alpha-fetoprotein, but also acute and chronic hepatitis, testicular cancer, ovarian tumor, malignant teratoma, pancreatic cancer, gastric cancer, intestinal cancer, embryonic tumor of reproductive origin, and women in pregnancy may also have elevated alpha-fetoprotein, but the degree of elevation is not as obvious as that of primary liver cancer. In benign liver disease, alpha-fetoprotein is mostly transiently elevated and lasts for less than one month. On the other hand, in primary liver cancer, the value of alpha-fetoprotein often exceeds 400 μg/L, and can be maintained at a relatively high level for a longer period of time.