Objective: To analyze the risk factors for postoperative complications of the elderly patients with primary retroperitoneal sarcoma(RPS). Methods: A retrospective cohort study was performed for elderly patients with primary RPS treated by soft tissue sarcoma multidisciplinary team Zhongshan Hospital from July 2009 to December 2020. Logistic regression analysis was used to find risk factors for postoperative complications. Results: A total of 98 cases were enrolled including male 54 cases and female 44 cases with 26 cases (26.5%) of age 70 years or older. Five-year overall survival following surgery was 61.2% (60 cases with 95% confidence interval, 49.1-73.7). Seventy-eight cases (79.6%) had tumor burden greater than 10 cm, and 87 cases (88.8%) with single lesion. There were 35 cases (35.7%) with well-differentiated liposarcoma, 31 cases (31.6%) with dedifferentiated liposarcoma, and 15 cases (15.3%) with leiomyosarcoma. A total of 96 cases(98.0%) underwent radical resection and 54 cases (55.1%) had more than one organ resected. The postoperative complications were found 55 cases (56.1%) and severe complications 16 cases (16.3%). Four cases (4.1%) died postoperatively. It was shown by multivariate analysis that both tumor burden greater than 10 cm (OR=4.597, P=0.012) and more than one organ resected (OR=4.858, P=0.003) were independent risk factors for postoperative complications in elderly patients with RPS. Conclusions: Operative treatment remained the preferred type for elderly cases with primary RPS and the surgery should be completed in high-flow centers of RPS.