Various multicrystal schemes have been widely used in the frequency conversion process of high power lasers or short-pulse lasers. Here we propose and numerically demonstrate a novel multicrystal scheme for improving the frequency-doubling efficiency of high-average-power lasers. Our proposed multicrystal scheme includes two different kinds of nonlinear crystals with opposite thermal properties, in which thermal-induced phase mismatches in the first crystal may be compensated by the next crystal. Asa result, the sensitivity of conversion efficiency to temperature deviations is reduced. The simulation results show that the temperature acceptance bandwidth of our two-crystal scheme is 5 times larger than that of common single crystal scheme. And a broader temperature acceptance bandwidth will be obtained if a three-crystal scheme is adopted. More important of all, the temperature-insensitive property of multicrystal scheme is independent of pump wavelength, which means it can be applied in various high-average-power laser systems.