The invention discloses a molecular marker, namely, an ITM2A gene used for the early diagnosis of esophagus cancer and an expression product of the molecular marker. According to the gene and the expression product, the QPCR and Western blot methods are adopted for proving that the ITM2A gene has different expressions in the esophagus cancer tissue and the normal esophagus tissue, and thus the ITM2A gene can be taken as an indicator for early diagnosis of the esophagus cancer. In addition, the invention further discloses applications of the ITM2A gene and the expression product of the ITM2A gene as targets for treating the esophagus cancer, so that the research and development of new drugs can be guided.