Liver cancer patients with persistently elevated AFP before treatment may help diagnose liver cancer, while after treatment may indicate poor treatment effect or recurrence and metastasis. Alpha-fetoprotein (AFP) is a laboratory test used in the diagnosis of liver cancer, mainly for liver cancer screening, diagnosis, determining the effectiveness of treatment and predicting recurrence. Pregnancy and gonadal embryonal tumor may also have elevated AFP, so based on the exclusion of pregnancy and gonadal embryonal tumor, AFP>400ng/ml is one of the conditions for the diagnosis of liver cancer. If AFP increases gradually without decreasing or >200ng/ml lasts for 8 weeks, it should be combined with imaging and liver function changes for comprehensive analysis or dynamic observation. About 30% of hepatocellular carcinoma patients have normal AFP level, and the detection of AFP heterogeneous body can help to improve the diagnosis rate. Even if radical resection is done for hepatocellular carcinoma, metastasis and recurrence still occur in 60%~70% of patients within five years. Therefore, patients should insist on follow-up after surgery, regular ultrasonography and detection of AFP, which can help to find metastasis and recurrence in early stage, and timely and active treatment.