Abstract: With the continuous improvement of the voltage level of flexible DC transmission technology, the reclosing scheme and isolation of the fault lines is particularly important. In this paper, a coordination strategy of the pre-current limiter and the capacitor clamped multiport DC circuit breaker is proposed, which has the advantages of low state loss, wide protection range, good economy and auxiliary reclosing operation. Firstly, the topological structure and the coordinated action sequence of the new circuit breaker are proposed. The fault is removed by using the principle of grid side boost, and then the branch thyristor is turned off by the LC oscillation; Secondly, the bus and the line faults are deduced respectively, and then the electrical parameters are designed for the blocking problem and the fault removal of the converter stations; Finally, the validity and applicability of the three-terminal DC network model in the PSCAD / EMTDC are verified, and the two kinds of fault simulation are analyzed respectively. Through the comparative analysis of the fault current, the system voltage and the branch voltage, it is verified that the circuit breaker is able to replace several conventional circuit breakers.