Abstract: In microgrid, transfer between different control mode is unavoidable, and it is essential to reduce the impact of frequency and voltage while transferring to guarantee the power supply quality. Firstly, we quantify and analyze the errors between different control strategies and present an optimized method for seamless transfer, including a dq-axis/reference phase angle calibration and a large disturbance instantaneous power compensation, and implementing calibration/compensation of modulation wave. Then, taking a hybrid DC system as an example, we adopt the above compensation strategy to design a DC power supply strategy for isolated microgrid that can achieve seamless transfer of control mode. The strategy includes the seamless access of the hybrid DC system to the isolated network and the seamless transfer strategy of control mode during large disturbances. Compared with the traditional seamless strategy, this strategy considers the coordination of the feeder/receiver sides in the DC transmission system and the reference phase angle error between different control modes, and provides certain instantaneous power support, thus the impacts caused by changes in the microgrid structure are reduced. Simulation results show that this strategy can not only achieve seamless transfer between different control modes, but also effectively support the frequency and voltage of the system during large disturbances in an isolated network.