Gastric cancer is a common solid tumor of the digestive system, This research aimed to investigate the relationships among CTHRC1 expression, prognostic values and tumor-infiltrating immune cells (TIICs) in GC patients.The expression of CTHRC1 in gastric cancer patients was analyzed using the GEPIA database and the TCGA database. The relationship between CTHRC1 expression and survival of gastric cancer patients was then explored using the Kaplan-Meier Plotter database and TCGA database.Subsequently, we explored whether there was an associative effect between the expression of CTHRC1 and TIICs in gastric cancer tissues. Then we constructed a prognostic model using immunomodulatory genes related to CTHRC1 and verified the specificity and accuracy of the model.Compared with normal tissues, the expression of CTHRC1 was significantly upregulated in gastric cancer tissues. And the high expression of CTHRC1 was associated with poor prognosis of gastric cancer patients.It is suggested that CTHRC1 is a reliable prognostic indicator for predicting the prognosis of gastric cancer patients.Then we successively used univariate and multivariate COX methods to obtain three high-risk immunomodulatory genes (TGFB2, CXCR4 and NT5E) and one low-risk immunomodulatory gene (TNFRSF18) associated with CTHRC1. These four immunomodulatory genes were used to construct a prognostic model for gastric cancer.Gastric cancer patients with high CTHRC1 expression have a poor prognosis and are associated with immune cell infiltration. Therefore, CTHRC1 can be considered as a potentially reliable prognostic indicator for gastric cancer patients.