The invention discloses a battery monitoring system and method of a vehicle and the vehicle. The battery monitoring system comprises a monitoring battery, a collecting assembly and a controller. The monitoring battery is connected with a braking energy recovery device of the vehicle and recycles motion energy of the vehicle so as to charge the monitoring battery and supply power to the monitoringsystem. The collecting assembly is used for collecting the current temperature of a power battery of the vehicle. The controller is used for controlling alarm equipment to give an alarm according to an early warning and alarming mechanism when the current temperature of a power battery pack is larger than a first preset value. By the adoption of the battery monitoring system and method of the vehicle, it can be effectively avoided that the power battery is repeatedly charged in the discharge process, the recycled motion energy is used for continuous battery monitoring when the vehicle is in astanding state, the battery safety and vehicle reliability can be effectively guaranteed, and use experience is improved.