Abstract: The predesigned Plate-type Advanced High Temperature Reactor (AHTR) used the uniform enrichment fuel assemblies, which resulted in the high power peak factor with its total power peak factor of 2.09. Thus, the safety and economy of the reactor are restricted to a certain extent. In this paper, different enrichment fuel assemblies were used to flatten the power. In order to speed up the search of the optimal loading pattern of the reactor core, an adaptive intelligent algorithm was adopted. The whole optimization process were completed by an automatically program written by MATLAB. The optimized power peak factor is reduced to 1.122, which is reduced by 25.02% compared with the original design. Simulation results of the temperature field show that the temperature distribution of the optimized reactor is more uniform. The maximum temperature is decreased from 1030 K to 1010 K, which greatly increases the temperature margin of the core.