Abstract: Based on the upper bound method of limit analysis theory, a failure model of axisymmetric high slope is proposed. The kinematically admissible velocity field and the statically equilibrium stress field are established. The external work and the internal energy dissipation of the excavated soil are calculated. According to the principle of work and energy, the equation of the upper bound solution for deep foundation excavation, that is, the expression of the stability ratio, is obtained. Considering three cases of rainfall, earthquake, and the coupling effect of rainfall and earthquake respectively, the upper bound solutions of foundation failure under different conditions are obtained, compared and analyzed. The results show that the internal friction angle of soil has a significant difference in the range of the plastic zone of foundation excavation. When the seismic acceleration coefficient increases from 0.1 to 0.2, the change of the stability ratio of foundation excavation is small, and the stability ratio decreases with the increase of the internal friction angle. When the pore water pressure coefficient increases from 0.2 to 0.25, the variation of the stability ratio of foundation excavation is large. This study reveals change mechanism of rainfall and earthquake on the stability of foundation excavation, as well as the quantitative relationship of their coupling effects, which can provide a theoretical basis for foundation stability analysis and support design.