The frequency characteristics of islanded microgrids are the basis for the feature analysis of microgrid， which is very important for the coordinated control of the microsources. Different power-frequency characteristics of the microsources are analyzed theoretically on the basis of the control algorithm， the transfer function and the structural features， which have different interfaces with the microgrid， such as inverters， synchronous generators and asynchronous generators. The analysis results show that different microsources have different frequency regulation functions， including the droop regulation function， the zero error regulation function and no frequency regulation function. The frequency characteristics of the microgrid are determined by the power-frequency characteristics of different microsources. The existence of zero error regulation function of microsources is a key for the frequency characteristics of the microgrid. The frequency characteristics of two simple microgrids and a complicated microgrid with different microsource combinations are simulated using PSCAD. The simulation results coincide with the theoretical analysis results， which verify the validity and effectiveness of the above conclusions. At the same time， the power distribution feature is derived for different microsource combinations.