To improve thermal capability of repetitive-rate laser,in this paper bonded Yb ∶YAG slices are chosen as gain medium, the doping-concentration in gain medium in chosen to be distributed in gradient manner. The distributions of stored energy, temperature and stress are obtained by calculating pumping process inside gain medium. From among the obtained results optimal parameters are chosen for an optimized design. The calculation indicate that using grad-doping medium can reduce temperature, deform, stress and wave aberration. In this paper, the feasibility of improving thermal-management by using grad-doping medium is demonstrated theoretically.