Disclosed in the invention is a fault protection method for a bipolar main wiring flexible direct-current grid. The method comprises the following steps that: region division is carried out, a unipolar region is divided as a polar protection region, a bipolar common region is divided as a bipolar protection region, a positive or negative line is divided as a polar line protection region, and a neutral line region is divided as a neutral line protection region; when a fault occurs, a fault location is determined and a corresponding fault handling strategy is employed based on the region where the fault is located; when the fault is located in the polar protection region, fault polar outage is carried out; when the fault is located in the bipolar common region, polar outage of a convertor station is carried out; when the fault is located in the polar line protection region, the outage of the region related to the fault line is carried out; and when the fault is located in the neutral line protection region, the fault is isolated and the grid works continuously. According to the method disclosed by the invention, four kinds of fault regions are divided according to the influence degrees of operation of the bipolar main wiring flexible direct-current grid by the fault location and the proper fault handling strategies are provided, thereby guaranteeing that the influence range of the bipolar main wiring flexible direct-current grid fault is minimized.