Objective: To investigated the clinicopathological features, immunohistochemistry and differential diagnosis of undifferentiated pleomorphic sarcoma(UPS). Methods: Th e clinical and pathological data of 10 patients with UPS were collected. Th e histological morphology, immunophenotype and prognosis were retrospectively studied. Results: Among the 10 patients with UPS, 8 were male and 2 were female, with a male-to-female ratio of 4:1, age of 45–73 years(average 57.7 years), tumor diameter of 1.5–7.0 cm(average 3.9 cm). Tumor cells were fusiform and pleomorphic in a bundle, interlaced or mat-like shape. Nuclear fission was easy to see, showing multi-nuclear giant cells and interstitial inflammatory cell infiltration. Immunohistochemical staining showed the could expression of Vimentin, CD68, HMB-45, S-100, CKpan, SMA, CD34, Desmin. Conclusion: Th e clinical symptoms of UPS are non-specific, and the diagnosis depends on pathological morphology and immunohistochemistry. UPS needed to be differentiated from gastrointestinal stromal tumors, pleomorphic liposarcoma, pleomorphic leiomyosarcoma, pleomorphic rhabdomyosarcoma, mucinous fibrosarcoma, poorly differentiated carcinoma, and malignant melanoma.