Objective To invetigate the clinical pathological characteristics, differential diagnosis features and prognosis of alveolar soft part sarcoma (ASPS) . Method 25 cases were studed by the clinical pathological characteristics, immunohistochemical expression, molecular genetic features and related prognostic information. Results There were 10 male and 15 female patients. Ages ranged from 10 to 52 years ( mean 24 years) . Tumors occurred in 16 cases of limbs, 3 cases of parenchymal internal organs, 3 cases of head and face, and 1 case each of the remaining trunk, vulva and retroperitoneum. The gross appearance of the tumor was dark red or gray white. Microscopically, it showed typical organ like, acinar and cytological features. Immunohistochemistry results showed that the positive rate of TFE3 in the nucleus was 100%, in addition, the MyoD1、Vim、CgA、DES showed different degrees of expression; the cells proliferation index of Ki67 was 5%~25%; the other markers were negative expression. Fish test results showed that TFE3 gene was abnormal. Conclusion The origin of ASPS is unknown and often locate on the limbs of young patients, which is characterized by TFE3 protein and gene expression.Pathological examination is the most reliable evidence for the diagnosis of the tumor. As the molecular mechanism of the tumor continues to be understood, targeted therapies may have great potential in the future.