Abstract: Objective: To investigate the influence of hyperthermic intraperitoneal chemotherapy (HIPEC) on the prognosis and postoperative complications in patients with peritoneal metastases of gastric cancer peritoneal cancer index (PCI)≤7. Methods: One hundred and twenty-four patients diagnosed with metastases of gastric cancer at The Fifth Clinical College of Shanxi Medical University from January 2019 to January 2021 were enrolled in this study. Their clinical characteristics were recorded and retrospectively analyzed. These patients were then assigned into two groups (intervention and control) according to whether suffering HIPEC. The prognosis of all the patients was followed. Kaplan-Meier and Cox multivariate analyses were performed to explore the impact of HIPEC on the survival rate of patients with gastric cancer. χ² test was used to analyze the relationship between HIPEC and patients' quality of life and the occurrence of postoperative complications. Results: The 1- and 2-year cumulative survival rates of the intervention group were 92.1% and 81.2%, respectively, which were significantly higher than those of the control group (75% and 63.3%, respectively). Cox multivariate analysis suggested that HIPEC reduced the mortality risk, and the 2-year risk of death was reduced to 0.341 times that of the control group. There was no significant difference in the level of postoperative quality of life improvement measured using Karnofsky score (KPS) between the two groups (P=0.602). HIPEC reduced the probability of febrile complications (P<0.05). There was no statistically significant difference between the two groups in terms of other postoperative complications. Conclusions: HIPEC significantly improves the prognosis of patients with gastric cancer and peritoneal metastasis, without increasing the risk of complications or damaging the postoperative quality of life.