There discloses a battery protection device. The battery protection device has a housing, a shunt device (4) disposed within the housing, and a positive connecting terminal and a negative connecting terminal coupled to a battery. The shunt device comprises an energy storage apparatus (1), a stabilizing circuit (3) for stabilizing the voltage of the energy storage device, and a voltage detection and display device (2) for feeding back in real time a terminal voltage of the energy storage device. The energy storage device is coupled in parallel with the stabilizing circuit and the voltage detection and display device. The positive connection terminal is coupled to a positive terminal of the energy storage device; and the negative connecting terminal is coupled to a negative terminal of the energy storage device. A battery device comprises a battery, said battery is provided with poles, and further comprises the battery protection device. The battery protection device is attached to an exterior of the battery via a double-sided adhesive. Connectors (5) at free ends of the conductive cables of the positive connecting terminal and of the negative connecting terminal are configured to encircle the poles to connect the battery protection apparatus in parallel with the battery. The battery device provides stable discharging and has an improved lifetime.