The invention relates to an AC excitation inverter combining with water cooling and air cooling, which comprises power cabinets and four reactor cabinets mirrored on both sides of the power cabinet. One side of the power cabinet is provided with a main inlet pipe and a main outlet pipe of the reactor cabinet which extending inward and passing through the side of the reactor cabinet. Three rows ofmodules are provided side by side in the power cabinet, one side of each row is provided with a branch inlet pipe connected to the main inlet pipe, and the other side is provided with a branch outletpipe connected to the main outlet pipe. The modules are respectively communicated with a branch inlet pipe and a branch outlet pipe through a module water pipe. More than three fans are provided sideby side in the middle of the rear side of the reactor cabinet, and an air inlet holes are provided at the bottom of the reactor cabinet. A heat dissipation mode combining water cooling and air coolingis adopted in the AC excitation inverter, which can reduce the overall costs while satisfying the heat dissipation requirement of the inverter.