Abstract: The clearance of DC faults is a key issue in DC power grids. Basing on the method of capacitance inserting into fault circuit mentioned in some literatures, a bucking-clamping DC circuit breaker was proposed which clears faults by the clamping and limiting function of pre-charge capacitance inserted into fault circuit. The topology and principle of the scheme were analyzed and designed such as reclosing and backup protection were made. The feasibility of the proposed scheme was verified by PSCAD/EMTDC simulation and hardware experiments, and detailed economic analysis was made as well. Compared with other schemes, the main advantage of this scheme is to achieve decoupling of fault isolation and energy consumption, first fast isolation and then slow consumption. The scheme has certain advantages in rapidity, and needs no lightning arresters, so it has certain engineering value.