The application of droop control in microgrids is analyzed in theory. The rationality and superiority of the method used in high-voltage microgrids based on solid state transformer（SST） are given. The relationship between droop coefficient and system dynamic performance is studied， and the influence of droop coefficient on the stable range of frequency is analyzed. Droop control is achieved through high-voltage converter of SST， and the relationship between droop coefficient and capacity of SST is given as well. A circular high-voltage microgrid is established， the effect of proposed droop control method on stabilizing frequency and voltage in grid-connect mode， islanding mode and the switching period between two modes is simulated and analyzed. Results show that the voltage and frequency of microgid has good stabilizing performance in different modes.