In the DC power system, the circuit breaker must not only complete the rapid disconnection and isolation of the high short-circuit fault current, but also undertake the frequent switching tasks of the small load rated current. First of all, this research adopts the topological structure of double-breaker series connection and introduction of auxiliary oscillating branch on the basis of forced commutation.Different control strategies can be adopted according to different current levels, which can realize the rapid breaking of small currents while improving high current breaking performance.Secondly, through the mathematical analysis of the working process of the circuit structure, and based on the PSCAD/EMTDC electromagnetic transient simulation software, the influence of different branch parameters on the breaking process is analyzed, and the circuit parameter optimization design is carried out for the breaking process of different load current levels.