Abstract: The Altyn fault is a major strike-slip fault system that consists of the main fault and the second-order faults with a distribution pattern corresponds to the 1eft-lateral strike-slip transpression model. The Changma basin is located to the south flank of the eastern segment of the A1tyn fault zone. whose paleo-stress field is in accordance with kinematic direction of the Altyn fault. The northern border fault of the Changma basin is the east segment of the Altyn main fault. The south border makes up the zigzag Banjiezijing-Yemashan fault，the Yerneshan mountain fault，the Shibandun. Gongchakou fault，and the north border fault of the central Oilian mountain，which ere S fracture，smal1 Y fracture，P shear，and S second-order fracture of the Altyn fault respectively The eastern border is composed of the west Xiangmaoshan fault. The Meshetou fault，and the Qingshiyan fault，which ere X fracture，S fracture，and R’s shear of the Altyn fault respectively. The Changma basin is a narrow triangle in map view surrounded by those fauls Therefore. we conclude that the Changma basin is a strike-slip branch basin formed by interaction of the Altyn main fault and its branch faults. During the Jurassic-Cretaceous，the Changma area was tensioned and buried by thick deposits. From the later Tertiary to Quaternery， the Changma strike-slip branch basin inversed and was pressed horizontally caused by the emplacement of the sinistral strike-slip Altyn fault. Having analyzed the petroleum geological features of the Changma basin，the authors emphasize that there are advantageous conditions of hydrocarbon genesis in the Changma basin，and more attention and investment should be devoted to the exploration in this area.