The strength reduction theory of the shortest path was used in the analysis of finite element strength reduction and limit equilibrium strength reduction,the cohesion and internal friction angle were assumed to be reduced by different reduction factor,and the reasonable reduction ratio of cohesion to internal friction angle was discussed in the case of double parameter strength reduction.Considering the influence of the buried depth of the tunnel and tunnel span,the existence of strength reduction of the shortest path in the limit analysis of shallow buried tunnel was proved.The results show that,in the shortest path of the strength reduction of shallow buried tunnel,with the increase of cohesion and internal friction angle reduction ratio，the reduction factor of cohesion increases gradually,the reduction factor of internal friction angle decreases gradually,the reduction path length decreases first and then increases, the reduction ratio and path length approximation follow a parabolic distribution,which proves the existence of the shortest path.In the shortest path of the strength reduction,the reduction range of the cohesion is greater than the internal friction angle,and with the increase of buried depth,the reduction range is gradually approaching.