Under the situation of considering the soil nailing effects on stability of soil side-slope,according to the damage model of the slip surface, the limit equilibrium theory and pseudo static approach,the seismic stability model and search model of the most dangerous slip surface are set up. The function relationship between stability coefficient and the center of circular slip surface is derived. Errors should be induced in calculating horizontal seismic inertial force and anti-sliding moment according to vertical slice. The seismic stability analysis method of slope protected by soil sailing is improved by using horizontal and vertical slice method. Calculation of the stability of slip surface is carried out by using the genetic algorithms. It can avoid getting in local minimum in optimal design. Using object-oriented programming language VC++, a computing program is implemented to make the optimization course reality. Finally,the method is applied to a case record. The results show the proposal method is credible.