Abstract: The fault response of microgrid is different from that of conventional distribution network because of the high penetration rate of inverter-interfaced distributed generators (IIDGs). Therefore, conventional protection schemes cannot be directly applied to microgrid. A novel protection method based on coordination of control and protection is proposed in this paper. The non-power frequency characteristic of IIDG is firstly studied. Then schemes based on single IIDG injection and multiple IIDGs injection are compared. A multiple IIDG based injection strategy, the tuning principle of filter parameters at the point of common coupling (PCC), and the starting criterion of multiple IIDGs injection are proposed. Corresponding IIDG controllers are designed as well. The simulation results show that when a fault occurs, all the IIDGs can start the feature frequency output in a short time; while significant feature frequency signals can be detected in the grid. By synthesizing the results of theoretical analysis and simulation, it can be concluded that the proposed system can handle the problem of feature signal shunting and coordination of multiple IIDGs, which provides both theoretical support and practical solution to all types of injection protection schemes based on over current, fault component, etc.