Abstract: The voltage droop controller is fairly suitable for the voltage source converter based multi-terminal direct current（VSC-MTDC）system when the system has more converter stations or the system power fluctuation is high.But many problems will occur when using traditional voltage droop control.A novel optimized droop control strategy is proposed for solving the problem caused by the inappropriate droop slope and complex VSC-MTDC system.It mixes together traditional voltage droop control and voltage margin control,and then provides the active power-voltage characteristic curve of optimized droop control.A four-terminal voltage source converter based high voltage direct current transmission system is built for simulation verification based on MATLAB/Simulink.Simulation results show that the optimized droop control can avoid problems caused by droop oversized or undersized slope,could reasonably allocate the active power of the stations and quickly stabilize direct current voltage.