According to the regional geophysical data, the Altun-Qilian arc giant gravity gradient zone is located at the northeastern edge of the Qinghai-Tibet block and forms the boundaries between Qinghai-Tibet block, Tarim basin and North China block. With the NEE-trending gravity gradient zone, this zone reflects the Altun fault characterized by both sinistral strike-slip and thrust. West Qilian is characterized by alternate NWW-trending arc gravity high and gravity low, which reflects the framework of squeeze nappe, thrust superposition and basin-range coupling within the Qilian orogenic belt. Between Dunhuang and Jinta, due to the tail effect of northeast Altun fault, a series of NNE-trending pull-apart fault basins associated with NEE-trending strike-slip fault and filling of mainland alkaline basalt in the pull-apart space were produced, which caused corresponding magnetic anomalies characterized by gravity low. Due to energy reduction and conversion, the Altun fault terminated in Huahai fault of Jinta basin, thus not extending eastward.