The theory of thermal-induced-depolarization is analyzed, the distribution of depolarization is numerically simulated, and the result is verified by the polarized light interferometry. The experimental result is coincident with the numerical simulation, which shows that the distribution of depolarization in the cross section of Cr,Tm,Ho:YAG is crisscross, and increases with the pump energy increasing. The direction of the worst depolarization is 45 with respect to the polarization direction of the polarizer. According to the numerical simulation, we employ a /4-plate to compensate the depolarization of a high-energy Cr,Tm,Ho:YAG laser. The pulse energy increases by 24% after compensation.