Abstract: A water-cooled heat dissipation module assembly capable of cooling a power module of a vehicle driving inverter system using a battery or fuel cell. The water-cooled heat dissipation module assembly includes a housing unit provided in the form of a housing having an opening portion at least partially opened at one side thereof. The housing unit and at least a part of a rim region of the cooling unit are made of a plastic material, and the housing unit and the cooling unit are joined to each other by plastic welding using a laser.