Abstract: To improve the operation reliability of multi-terminal DC grid with DC faults and reduce the interrupting capability requirements of DC circuit breakers, this paper proposes a topology of DC circuit breaker with pre-current-limiting capability for DC grid. In the proposed topology, the current-limiting circuit can be put into operation in advance when the overcurrent appears in the grid, and it can be decided to interrupt the fault current or recover to normal operation according to the fault detection results.This topology adopts auxiliary capacitor and half-controlling device thyristor to achieve the fast switching of current-limiting inductor and the fast interruption of fault current, which can effectively limit the fault current and has certain economy. To verify the feasibility of the proposed topology in terms of pre-current-limiting and fast interrupting, a simulation model of four-terminal DC grid is built in PSCAD/EMTDC. Simulation results verifies the effectiveness of the proposed topology in limiting fault current and isolating faulty lines.