In order to solve the problem of low accuracy in predicting the instability risk of foundation pit slopes under earthquake action, a seismic stability analysis model was constructed based on limit analysis theory in this study. Firstly, an underground continuous wall enclosure structure was set up and a seismic stability analysis model using MICHALOWSKI/DRESCHER was established. Then, considering different working conditions comprehensively, the cow horn damaged body was inserted into the block as a model, and seismic stability analysis conditions were se. Finally, based on the theory of limit analysis, the virtual power equation was established by calculating the gravity power, seismic force power, and internal energy dissipation rate on the sliding surface, and then the upper limit of the seismic stability coefficient was solved. The results show that when the aspect ratio of the slope from 0.15 increases to 3.56, the seismic stability coefficient drops sharply by 561%. The soil displacement caused by vertical upward seismic force is 0.879 8 m, which is 3.3% higher than the downward displacement; The displacement under the combined seismic load is 0.939 0 m, which is a maximum increase of 10.0% compared to a single direction. Compared to the reinforcement density is 0.2， when the reinforcement density is 2.6, the stability coefficient increases by 28.4%. The proposed model can provide theoretical basis for the design of foundation pit support in high-intensity areas and reduce construction risks.