ObjectiveTo summarize the diagnosis and treatment of a primary gastric colon cancer, and to explore its safety and feasibility.MethodThe clinical data of a patient with gastric cancer and sigmoid colon cancer who admitted to The Affiliated Yantai Yuding Hospital of Qingdao University in October 2017 was analyzed.ResultsThe patient underwent laparoscopic radical gastrectomy plus π anastomosis and laparoscopic radical resection of colon cancer. The operation time was 330 min and the intraoperative blood loss was 120 mL. There were no complications such as stomach cramps and sputum after operation and he was successfully discharged on the 9th day after surgery. Postoperative pathological staging: gastric cancer (pT3N3M0, ⅢB) and sigmoid colon cancer (pT2N0M0, Ⅰ B).ConclusionsMultiple primary cancer of the simultaneous gastric colon should be diagnosed before operation. Laparoscopic minimally invasive treatment for gastric cancer with sigmoid colon cancer is safe and feasible, and can benefit patients.