Abstract: The stability of loess landslide is quite important in geological investigation, which needs to be evaluated in combination with regional seismic conditions. This paper evaluated a loess landslide in Shuiwan, Maiji District of Tianshui city by means of parallel electrical method and numerical simulation. The parallel electrical method is to explore the fine layers on the landslide mass and determine the occurrence state and the parameters of the main sliding surface in order to accurately construct the numerical model for the landslide mass in Shuiwan, and further analyze its dynamic response characteristics under the earthquake load; at the same time, various methods are used to calculate the stability safety factors under three circumstances of natural state, small earthquake and large earthquake. The coefficients obtained from the strength-reduction method are 2.942, 1.99 and 0.683, respectively. The results show that slide failure happen in loess landslide mass under large earthquake. The process is that the upper part of the landslide is cracked in the early stage, and the middle and lower parts are sheared. With the continuous seismic waves, the shear in the upper and lower slopes is connected, and the sliding surface is formed. The results of on-site detection and numerical simulation provide guidance for landslide prevention and reference for the stability evaluation of similar landslides.