The invention discloses a direct-current breaker used for a multi-terminal direct current system and a control method of the direct-current breaker. The breaker comprises a lightning arrester, a main switch branch circuit and auxiliary switch circuits, wherein the lightning arrester is in parallel connection with the main switch branch circuit. The main switch branch circuit comprises two breaking units which are identical in structure and in serial connection, wherein each breaking unit comprises a direct-current load switch and a thyrister valve section, and the direct-current load switch and the thyrister valve sections are in serial connection. The two ends of each breaker unit are in parallel connection with the auxiliary switch circuits which are identical in structure. Each auxiliary switch circuit comprises a thyrister-reactance serial-connection branch circuit, a diode, a capacitor and a resistor, wherein the diodes are connected to the two ends of the breaking units in parallel, and each thyrister-reactance serial-connection branch circuit and each capacitor are in earth parallel connection with the two ends of each corresponding diode and are grounded through the resistors. In the method that reverse currents are implanted, direct currents of the main switch branch circuit cross zero to be cut off, and load currents are cut off through a direct-current load switch in the structure of the direct-current breaker.