The invention discloses a rapid fault diagnosis method used for a microgrid, which adopts a mode of step-by-step diagnosis and comprises the following steps that firstly, primary diagnosis is carried out by utilizing the switch information of a network, i.e. newly added passive sub-networks are judged as fault regions and fault elements according to the difference of before and after topology analysis results of faults, and for simple faults, a unique fault region and fault element can be determined. For complicated faults, a plurality of suspected fault solutions can be possibly presented in the result of the primary diagnosis of the switch information. At this moment, a second-step diagnosis is entered, and the diagnosis is carried out by utilizing the protection information of the network. A new target function is established in protection information diagnosis by utilizing the protection information of the elements; the fault diagnosis problem of the microgrid is expressed as the 0-1 integer programming problem; a genetic algorithm and tabu search mixed strategy is introduced to solve the target function; and the fault elements are determined by the optimal solution. The invention can effectively improve the fault diagnosis efficiency, reduces the time of fault diagnosis and improves the fault diagnosis quality.