The present invention provides a power battery cooling system. The battery includes a plurality of battery cells. The battery cells are arranged in a matrix form inside a battery box. The cooling system includes a water pump, a water channel, and a heat radiator. The water pump is installed in the water channel, the heat radiator communicates with the water channel, and the water channel includesan outer waterway and a circum-battery cell waterway, the circum-battery cell waterway is disposed around the battery cells. The outer waterway includes a main circulating waterway and a micro circulating waterway. The circulating waterways can be selected according to demands by setting of the two sets of waterways, energy consumption can be effectively reduced, and further temperature stabilityand consistency of the battery cells can be guaranteed by arrangement of phase change material cooling equipment.