The invention relates to a collision protection method and a device for the electric vehicle. The collision protection method includes the following steps that a pulse signal of start current used forstarting a safety bag is obtained; according to the pulse signal of the start current, a power-off instruction is generated; the power-off instruction is sent to a high-voltage power supply unit to make the high-voltage power supply unit to cut off the output of high voltage electricity. The method and the device can largely shorten the response time from the occurrence of a collision accident tothe disconnection of high voltage electricity, the risk of fire caused by the short circuit of a high voltage power supply and other faults after the collision of vehicles is reduced, and the safetyof the vehicle is improved.