In mountainous areas, casualties caused by earthquake-induced landslides often account for more than half of the total earthquakes. Especially in the loess area, due to the far-distance loess landslide caused by the earthquake, the disastrousness is even more serious. This paper attempts to solve the problems of earthquake-induced loess slope instability such as peak acceleration, critical displacement and moving distance. It uses discrete element(PFC)method, calibrates the stress-strain curve of the indoor three-axis experiment, and transforms high-precision aerial three-dimensional topographic data. It takes the loess slope in Haikou Village, Ningxia Province as the research object to carry out numerical simulation of slope unstable failure and movement process under the three-dimensional earthquake. It monitors the stress components at different locations under the earthquake, compares the p and q values of the monitoring points with the p-q failure lines obtained from the indoor three-axis experiments. It obtains the stress paths and peak accelerations in the process of slope failure. Combining with the maximum displacement of the monitored particles, the critical maximum displacement of slope failure is obtained. The peak acceleration of the slope failure is 0.135g and the critical displacement is 50 cm. At the same time, according to different ground environmental conditions, the damage range of the slope after sliding failure under different friction coefficients is predicted. The paper provides a new visualization method for the seismic design and earthquake prevention and mitigation of slope engineering in the loess area.