Aiming at the complicated control strategy of the multi-reactor nuclear power plants, a simulation method was used to study. Combining the composition and operation characteristics of the multiple nuclear reactors, the unit’s operation plan was put forward. Then the paper discussed the controller and operation mode of steam supply system under unequal load. To verify and validate the designed control strategy and controller, in the simulation experiment of transient variable condition, 2 typical working conditions of unequal load including parallel rising and parallel falling the load are simulated. The simulation results show that the choice of controller design and control scheme can meet the safety and stability requirements, and can provide reference for research on control strategy of multi-reactor nuclear power plants.