The invention belongs to the technical field of medical biology and particularly discloses a marker and a kit for cardia cancer diagnosis. The marker for cardia cancer diagnosis, provided by the invention, is at least one of 3, 4-Dihydroxybenzeneacetic Acid, 1, 5-Androro-D-Glucitol and 3-Methylxanthine, and a detection reagent of the marker can be used for preparing a cardia cancer diagnosis product. The invention also provides a kit for cardia cancer diagnosis, the kit contains a detection reagent for detecting the marker in the first aspect, and the detection reagent is a reagent for detecting the marker in a sample through chromatography-mass spectrometry or chromatography-mass spectrometry. The cardia cancer can be effectively detected by detecting expression levels of 3, 4-Dihydroxybenenoic Acid, 1, 5-Androdro-D-Glucitol and 3-Methylxanthine in human serum, detection sensitivity is as high as 90.0%, specificity reaches 91.0%, and the kit can be used for large-scale screening of asymptomatic crowds in a cardia cancer high-incidence area and is beneficial to screening and early discovery of asymptomatic high-risk crowds.