Abstract: Reactor with 177-fuel-assembly core usually operates in G mode and the core boron concentration requires to be adjusted during the load following. Limited by the capacity of the boron recycle system, the load follow capability is available only for 85% of the lifetime. In order to improve the load-following capability of 177-fuel-assembly core reactor and extend the lifetime of the load following, a mechanical compensation control strategy based on 177-fuel-assembly core was studied. Different arrangements of control rods are designed. The control rod worth, the impact of power peak and the control ability during load follow are analyzed. Based on the optimized arrangement of control rods and the mechanical compensation control strategy, the whole-life base load operation, the end-of-life 90% load cycle load tracking and the starting process simulation are carried out. The results show that under the proper arrangement of the control rods, 177-fuel-assembly core can implement mechanical compensation control strategy, and the load following capability has reached the international advanced level.