Combining the characteristics of slab lasers and disk lasers,a new surface gain Zig-Zag slab was designed by geometrical optics,and it takes Nd∶YAG as gain medium.The selection method of the end face cutting angle was analyzed,and the geometrical parameters of Zig-Zag slab were designed through the Tracepro simulation.Finally,the optimal doping density of 0.4 at% was determined,and the absorption efficient of the slab reaches to 97%.