Abstract:The Longquanshan fault zone is a regional fault which is located between strongly concaved block of western Sichuan basin and stably uplifted block of middle Sichuan.After the Wenchuan earthquake in 2008,the earthquake risk potential of this fault has been greatly concerned.In this paper,the distribution,late Quaternary activity,deep structure and formation mechanism of Longquanshan fault zone are discussed.It's possible that the north segment section of Longquanshan fault zone is distributed along the west side of Lonquanshan mountain at east of Deyang city.The fault emerges in both wings of anticline on the middle segment of the fault;and the south segment of the fault is mainly W-dipping.The fault has been active since Late Pleistocene.The previous terrace investigation demonstrated that the fault zone even actived in Holocene.Considering the evaluating the earthquake risk potential of this fault,further investigationg on the activity time,deep structure and movement mode of the fault zone is deserved to be done.