The invention discloses an electrical system for a pure electric vehicle. A positive end bus high-voltage direct current contactor, a negative end bus high-voltage direct current contactor and a high-voltage safety switch are arranged between a battery management system of the electrical system and a driving motor controller; and a key switch is used for controlling low-voltage power supply relays of all electrical parts. When the electric vehicle is stopped to be charged, a vehicle-mounted charger independently supplies power to a low-voltage power supply end of the battery management systemand a high-voltage direct current bus; when the key switch is adjusted to an ON position, all of a vehicle controller, the battery management system and the vehicle-mounted charger have no serious faults, and the negative end bus high-voltage direct current contactor, a precharging high-voltage relay and the positive end bus high-voltage direct current contactor are sequentially closed; and when the key switch is adjusted to a Start position, the electrical system can accept an instruction of a driver to drive the vehicle to run. When the key switch is switched on, an electric power-assisted steering device, an electric air conditioner, a braking power-assisted vacuum pump, an electric pump and an electric cooling fan are all controlled to work, and a low-voltage storage battery is charged through buck DC / DC.