The basic characteristics of the wavefront aberration of Yb:YAG slab laser were analysed. Combined with spot shape and power density, a double deformabe mirror combined of water cooled 1D DM of 13 units and 2D DM of 95 units was proposed to correct the wavefront aberration of Yb:YAG slab laser. According to the characteristics of the output laser, the calibration demand analysis and calibration capability analysis were carried out. Based on this, the simulation and optimization design of the 1D DM and 2D DM were improved. The beam quality of the laser was improved from 9.03 to 1.98 in the correction experiment. The beam quality correction ability of the adaptive optical system with double DM combination mode for Yb:YAG slab laser was verified.