Abstract： Objective:To investigate the diagnostic value of CT and MRI in primary retroperitoneal liposarcoma (RPLS) .Methods:A retrospective analysis was performed of 106 patients with primary retroperitoneal liposarcoma admitted to Yantaishan Hospital between June 2010 and June 2019. All patients underwent CT and MRI. The imaging characteristics were analyzed. By using surgical pathological findings as the gold standard, consistency of CT and MRI in diagnosing primary RPLS was investigated.Results:Among the 106 cases, postoperative pathology revealed 22 cases of highly differentiated, 59 of dedifferentiated, 16 cases of mucinous, 2 cases of round-cell, and 7 of pleomorphic RPLS. Preoperative CT correctly identified tumor differentiation in 92 cases, with an accuracy of 86.79% for all types, 100% for well-differentiated, 91.37% for dedifferentiated, 93.33% for mucinous, 33.33% for round-cell, and 20.00% for pleomorphic liposarcoma. Preoperative MRI correctly identified tumor differentiation in 96 cases, with an accuracy of 90.57% for all types, 100% for well-differentiated, 96.49% for dedifferentiated, 85.71% for mucinous, 40.00% for round-cell, and 62.50% for pleomorphic liposarcoma. Consistency test indicated that good diagnostic consistency between CT and MRI (Kappa=0.813, P=0.000) . Conclusion:CT and MRI are of important value in diagnosing primary RPLS of various differentiation. This should warrant more attention to their clinical use.