The invention relates to the technical field of converter station power control, in particular to an MMC-HVDC converter station power control method and system based on the simulation of characteristics of a synchronous motor. The method comprises the following steps: adding an additional power controller to an HVDC converter station based on the simulation of characteristics of the synchronous motor; performing the switching control of the additional power controller, i.e., judging whether the additional power controller works in an active state or not, responding to the fact that the additional power controller works in the active state, and achieving the selective switching of the additional power controller through hysteresis control of the frequency offset ferr. In order to eliminatethe offset of the transmission power of the converter station caused by static random fluctuation of the local power grid frequency, the additional power controller for correcting a frequency nominalvalue in real time by using an active power offset integral is designed, thereby solving the problem that the active power cannot be accurately controlled when the synchronous motor simulates and controls static random fluctuation of a local power grid frequency, and achieving the selectivity that a main power grid participates in local power grid adjustment through a DC system.