With the formation and development of multi-area power system and the continuous increasing proportion of installed units, nuclear power plants (NPPs) are facing great pressure on multi-area interconnected power system regulation. The load following capability of generating units plays a crucial role in ensuring the operation safety and stability of both NPPs and power system. At present, advanced pressurized water reactor (PWR) has a certain capability of load following. Compared with traditional large single module PWR NPPs, multi module NPPs consisting of several small modular reactor (SMR) such as modular high temperature gas-cooled reactor (MHTGR), have remarkable differences in both process structure and operation characteristics, such as the sixmodular MHTGR plant HTR-PM600. To study and verify the feasibility and performance of HTRPM600 on regulating frequency and tie line power in multi-area interconnected power system, a dynamic modeling of multi-area interconnected power system is given firstly to simulate the power grid futures. Then a new control strategy is proposed on the existing unit coordinated control system. Finally, the numerical simulation is conducted and the results show that HTR-PM600 can control frequency and tie-line power well in the operation control of multi-area interconnected power system. At the same time, the operation indexes of HTR-PM600 plant also meet the requirements.