The activity of the NWW striking South Guinan fault that developed in the Keririgang mountain and northeast boundary of the Xinghai-Tongde basin is studied using Google Earth image data. Through remote sensing interpretation and field geological investigation, the fault was found to be mainly a thrust fault with a length of 157 km. Research on microlandform offsets indicates that the fault was last active during the late Pleistocene era and there have been no signs of movement since the Holocene era.