This kit is used for quantitative detection of CA19-9 in human serum in vitro. CA19-9 is a kind of mucin tumor marker with molecular weight of 10kDa. The mucin can be expressed in normal fetal and adult pancreas, gastrointestinal mucosa and liver tissue, and can be released into the intercellular substance and serum. In the serum, CA19-9 exists in the form of sialic acid. The level of CA19-9 in the serum of most cancer patients such as pancreatic cancer and hepatobiliary cancer is significantly increased. CA19-9 has a high detection rate for pancreatic, hepatobiliary, gastric, colorectal and other digestive tract cancers, especially pancreatic cancer, and has a certain clinical significance for the observation of curative effect and prognosis of malignant tumors, especially for the follow-up after surgery.