The invention discloses a novel combined DC circuit breaker topology, which adopts only one main breaker switch, one malfunctioning auxiliary switch, one transfer switch TS0 connected in series with the main breaker switch, two groups of diodes in different directions, and a transfer switch TS1 corresponding to m lines on each DC bus bar, wherein, the main breaker switch TS0 is connected with themain breaker switch TS0, and the main breaker switch TS1 is connected with the main breaker switch TS0-TSm. The transfer switch TS0 is connected in parallel with the failed auxiliary switch in serieswith the main disconnect switch, one end of the main disconnect switch is connected with the DC bus bar, the other end is connected with the diode group in the direction of the inflow line through thetransfer switch TS0, and is also connected with the diode group in the direction of the outflow line through the failed auxiliary switch. The transfer switch TS1-TSm is respectively connected to thebus bar and the corresponding line 1-Line m. When the system is in normal operation, the voltage on both ends of the switches of each part of the novel combined DC circuit breaker is zero, which can effectively reduce the breakdown probability of the device, improve the operation reliability of the system as a whole, adopt fewer main devices, and have better economy.