The invention provides a battery balancing apparatus. The battery balancing apparatus is applied to a battery module of a laptop computer. The battery module comprises a plurality of batteries and a plurality of switch units coupled in series. The battery balancing apparatus comprises a first multiplexer, a second multiplexer, a switch module and a controlling module. The first multiplexer is coupled to the anode of each of the batteries; the second multiplexer is coupled to the cathode of each of the batteries. The switch module is coupled to the switch units. When a cycle counting parameter meets a default condition, the controlling module controls the first multiplexer, the second multiplexer and the switch module to be in a specific mode to form a specific current path among the batteries.