The invention provides a battery pack heating method and system, and relates to the field of dynamic batteries. The method is applied to the battery pack heating system, and comprises the steps that a battery management system controls a battery pack to enter a connection state with charging equipment; the battery management system judges whether the temperature of a battery with the lowest temperature in the battery pack is lower than a first preset temperature or not; if the temperature of the battery with the lowest temperature in the battery pack is lower than the first preset temperature, the battery management system controls a heater to be in a heating state to heat the battery pack; the battery management system judges whether the maximum temperature difference among the batteries in the batter pack is larger than a preset difference, and the temperature of the battery with the lowest temperature in the battery pack is higher than a second preset temperature or not; if the maximum temperature difference is larger than the preset difference, or the temperature of the battery with the lowest temperature in the battery pack is higher than the second preset temperature, the battery management system controls the heater to be in a closing state. By adoption of the battery pack heating method, the battery pack can quickly reach the temperature requirement for charging.