The invention relates to a heat dissipation device and a heat dissipation module for a power device. The heat dissipation device for the power device includes a heat dissipation main body, a first working medium partition plate, a second working medium partition plate, a first cover plate, a second cover plate, a liquid inlet pipe and a liquid outlet pipe. According to the invention, the contact area of the power device and heat pipes and the heat exchange area between working medium flow channels and cooling fluid channels are effectively amplified, the thermal resistance between the workingmedium flow channels and slots is extremely small, the heat dissipation efficiency of the power device is high, and the heat dissipation device and the heat dissipation module are suitable for heat dissipation of a large power device. Laminated arrangement of the slots, the working medium flow channels and the cooling fluid channels are utilized to replace welding of multiple heat dissipation plates, a water inlet main pipe and a water discharge main pipe in the prior art, and therefore, excessive welding points can be avoided, manufacturing process is simple, the cost is low, the thermal resistance can be effectively reduced, the risk of cooling fluid leakage is reduced, and the heat dissipation efficiency is improved.