The invention discloses a collision detection device and method. The method comprises the steps that an airbag protection unit sends a collision signal, a battery management unit and a whole-vehicle control unit receive the collision signal separately, when it is judged that no fault occurs in a CAN signal access for transmitting the collision signal and it is judged that the collision signal is in a collision state through the CAN signal access, the battery management unit controls a battery unit to open the connection with loading, and the whole-vehicle control unit sending a second opening instruction to the battery management unit to make the battery unit open the connection with loading. In the collision detection device and method, the battery management unit and the whole-vehicle control unit detect the access and the state of the collision signal through the CAN signal access, so that when a fault occurs on any one of the battery management unit or the whole-vehicle control unit, the battery unit can still normally receive a control instruction, the connection is opened, the phenomenon is avoided that the battery unit cannot timely open the connection due to collision caused by a fault of a transmission channel, which causes a fire, explosion and the like of the battery unit.