A mixed type direct current breaker is composed of mechanical switches (17, 18 and 20) and power electronic devices (16, 19, 13, 14, 15, 21, 22, 23, 24, 25, 26 and 27). When direct current high-voltage transmission lines run normally, a low-loss current path is formed through the mechanical switches (17, 18 and 20) and the power electronic devices (16, 19, 13, 14, 21 and 22), and when the direct current high-voltage transmission lines break down, rapid disconnection is achieved through an electronic switch (19), and therefore rapid disconnection of the mechanical switch (18) under a zero current situation is achieved. The problem that a capacitor (15) and an inductor (22) cause current turn-off time to be long in an oscillation process is solved through control of power electronic circuits (13, 14, 15, 27, 21, 22, 23 and 26), and rapid tuning-off of fault currents is achieved.