Abstract: In order to solve the technical problems of fast clearing DC faults in DC grid, a multiport DC circuit breaker integrating current-limiting and fast fault clearing capabilities was proposed. Three control strategies were designed, including energization, fault interruption after current limiting and reset after current limiting. The proposed topology realizes a large reduction of current value at break time through a current limiting circuit. The time required for fault clearing is shortened by inductive bypass circuit. The proposed control strategy realizes the pre-charge of circuit breaker capacitor by multiplexing part of the topology loop. The operating sequence of circuit breaker is optimized by the method of preliminary fault judgment and secondary confirmation, and the current value at the break time is further reduced. A three-terminal DC grid simulation model is built in PSCAD/EMTDC, and various operating conditions of circuit breakers are simulated and verified. The results show that the multi-port DC circuit breaker can realize the protection of multiple DC lines, reduce the current value at break time and reduce the time required for fault interruption under all working conditions.