With micro-sources connected to the distribution network in the form of a microgrid， power supply is changed from unidirectional flow， radial structure into bidirectional flow， ring loop structure. The output short circuit current of the grid inverter will be directionally increasing and decreasing once the single-phase ground-fault occurs in the combined mode. Consequently， protective devices may cause malfunction and maloperation. To solve these problems， a new ground-fault protection scheme for closed-loop microgrid is proposed. In the scheme， the radial or trunk-style feeders are built into closed-loop connection. Where necessary， each section should be composed of protective devices including the first kind of protectors and the second kind of accelerated protectors. The first kind of protectors detect positive direction fault according to the one-end fault component phase angle. If the signs of the two protectors are both positive， the fault area is located. During acceleration， the second kind accelerated protectors detect the fault component criterion， and then rapidly isolates the fault section by use of the operating results of the opposite protector. It is shown that the scheme proposed is valid and feasible by theoretical analysis and simulation test.