The Changma fault consists of four sub-faults,and is an important transform fault located between the Altyn Tagh fault and the western segment of the Qilian Mountains.In 1932,a M7.6 earthquake occurred in the fault,forming a rupture with a length of approximately 120 km that is composed of a series of fissures,fault scarps,offset terraces,and gullies.The maximum horizontal and vertical coseismic displacement was up to 5.5 m and 1.9 m,respectively.A trench excavated at Choushuiliugou in the middle-eastern segment of the Changma fault shows evidence of two paleoearthquakes: one is the Changma earthquake (1932) and the other earthquake occurred after 902±44 a B.P..Combined with the results of previous studies,it was determined that seven paleoearthquakes have occurred in the Holocene. Base on characteristic earthquake model, we speculate an earthquake recurrence interval of approximately 1 ka,and part of paleoearthquake events are not revealed by the trench.The trench also shows that the dip direction of the layer on the hanging wall is opposite to that of the down wall and low-angle fault.Based on a survey of dislocation landforms,the ratio of horizontal shortening and left strike slip was found to be 1∶5.Eastern extrusion occurred in relation to the influence of Altyn Tagh fault activities in the study area.The change in fault trend has resulted in regional stress and differing angles between some of the fault segments,particularly the tip of sub-faults.Active fault characteristics are shown predominantly as sinistral strike-slip,but there is an evident increase in the component of horizontal shortening,which forms nappe activities on the hanging wall.It also forms a specific low-angle strike-slip phenomenon,which illustrates that the Changma fault has prominently presented crustal shortening since the late Pleistocene,in addition to absorbing much of the sinistral displacement of the Altyn Tagh fault,and playing a significant role in the tectonic transition between the Altyn Tagh fault and a series of faults in the western segment of the Qilian mountains.