Abstract：Based on field investigations of fault activity in the project region of the first stage of the west line of Water Diversion Project from South to North of China，following viewpoints are presented. (1) The NW directional faults mainly twist laevogyrately，and the SN directional ones are well developed and twist dextrorsely. (2) Because of the confining of Maerkang floor boming and Nianbao granite，the activity of faults shows a weakening trend towards SE direction. The activity and its engineering effect of regional faults such as Qingshuihebei fault present a trend of weakening，or a tend to terminating. (3) The influences of fault activity on the project are mainly the influences of the deformation of faults and fault belt and tectonic stress field on the deep tunnels，and the influences of fault on the earthquake induced by reservoir.
