In order to achieve power mutual benefit between AC and DC sub-microgrids in island mode, a power allocation method of coordinated hybrid microgrid system is proposed in this paper. Firstly, the topology of the microgrid structure is analyzed for gathering characteristic quantity which can represent the reference value of power transmission. In addition, the switching condition of the operation stage is designed reasonably according to the characteristic quantity, where the operating mode of the system is divided into the interlinking converter free control section and ILC working control section. Secondly, a power feedback algorithm based on AC side bus voltage and DC side voltage feedback is designed to achieve the power mutual benefit purpose. Finally, a simulation model is built in MATLAB Simulink. The simulation results show that the AC-DC sub-microgrid can bear the power fluctuation of the system according to its own conditions and ensure the overall stable operation of the system by using the power mutual benefit method proposed in this paper. Furthermore, the response time of ILC power change is less than 50ms in the simulation, which indicates that the control strategy has a high dynamic response.