Fucoidan is clinically referred to as α-L-fucosidase, and an elevation of 45 U/L is considered abnormal, and hepatocellular carcinoma or other liver-occupying lesions are mostly considered. α-L-fucosidase is widely found in lysosomes of human liver, brain, lung and other cells, mainly involved in the decomposition and metabolism of biologically active macromolecules such as glycoproteins, glycolipids and other substances containing fucoidan, and the normal reference value is (27.1±12.8) U/L. α-L-fucosidase can be elevated in hepatocellular carcinoma or other liver occupying lesions, especially the positive rate of hepatocellular carcinoma is more obvious, and it can be lowered after surgery of hepatocellular carcinoma, and recurrence can be considered if it is elevated again, so it can be used to judge the therapeutic effect of hepatocellular carcinoma, to judge the prognosis and to forecast the recurrence. If alpha-fetoprotein is combined with α-L-fucosidase, the positive diagnosis rate of primary liver cancer can be improved. In addition, α-L-fucosidase in patients with chronic hepatitis and cirrhosis is also elevated to a certain degree, but usually only mildly elevated. If α-L-fucosidase is elevated, it is necessary to find the cause promptly and follow the doctor’s instructions to treat it actively.