The utility model relates to a thermal management system for power battery installs in the battery box, including two at least core assemblies and water circulation pipeline, at least two the settingthat the core assembly connected in parallel each other is in water circulation pipeline last and with the water circulation pipeline intercommunication, the core assembly includes the water -coolingboard that two at least mutual series connection set up. The utility model discloses connect two at least core assemblies in parallel in water circulation pipeline, reduced whole thermal management system's complexity and manufacturing cost to including the water -cooling board that establish ties to set up in every core assembly, connected mode through connect and afterwards establishing ties earlier makes the flow field of whole core assembly and temperature field even, and the heat transfer is effectual, has avoided water circulation path overlength, leads to battery module's front and backhot management effect nonconformity.