System and method for safely powering on/off high-voltage circuits

The invention discloses a system for safely powering on/off high-voltage circuits, which is used for safely powering on/off the high-voltage circuit of an electric vehicle. The system comprises an electronic control unit, a first high-voltage circuit, a relay, a second high-voltage circuit, and a time sequence control circuit, wherein the electronic control unit is used for sending a high-voltage circuit connecting signal or a high-voltage circuit disconnecting signal; the first high-voltage circuit, the relay and the second high-voltage circuit are used for connecting or disconnecting a power battery and a motor; and the time sequence control circuit is used for sequentially controlling the connection of the first high-voltage circuit after receiving the high-voltage circuit connecting signal, controlling the relay to be connected if a current change rate detected by a current sensor is smaller than a threshold value, controlling the first high-voltage circuit to be disconnected if the current change rate detected by the current sensor is smaller than the threshold value, controlling the second high-voltage circuit to be connected after receiving the high-voltage circuit disconnecting signal, controlling the relay to be disconnected, and controlling the second high-voltage circuit to be disconnected if the current change rate detected by the current sensor is smaller than the threshold value. The invention further discloses a method for safely powering on/off the high-voltage circuits.