The invention relates to application of a reagent for detecting PITX1 (paired-like homeodomain 1) expression in the preparation of a gastric cancer prognosis evaluation kit, belongs to the technical field of biology and particularly relates to the field of medical diagnosis. The invention discloses application of a reagent for detecting PITX1 expression in the preparation of a gastric cancer prognosis evaluation kit. Predicted gastric cancer prognosis and chemotherapy resistance condition can be acquired by marking gastric cancer prognosis prediction and gastric cancer chemotherapy evaluation, and by using immunohistochemical method to detect the expression level of PITX1 gene; the PITX1 gene is simple to introduce; the whole predictive evaluation is simple and easy and is highly feasible.