The present invention relates to a method and device for preventing external failures from wrongly jumping to an abnormal bus coupler/segment under double buses and a single component. The method or device comprises the following steps: when bus coupler/segment current is abnormal, acquiring steps or units of regional differential protection ranges corresponding to the abnormal bus coupler/segment; judging whether current features in the regional differential protection ranges satisfy regional differential protection criteria or not, and if yes, opening an action exit of a corresponding bus coupler/segment breaker; and otherwise, implementing a step or unit of locking the action exit of the corresponding bus coupler/segment breaker. According to the method and device disclosed by the invention, the technical problem that when the bus coupler/segment current is abnormal, the external failures of the buses are wrongly jumped to the abnormal bus coupler/segment breaker under a double-bus and single-component wire connection mode in a bus protection process can be solved.