A high power density DC-AC power inverter includes a casing corresponding to a rack. The casing has air inlets and air outlets arranged in a honeycomb shape and a fan unit. The casing is provided with two choke coils and a heat sink therein. The heat sink includes fins facing downward. A plurality of power elements are laterally provided on top of the heat sink. The heat generated from the power elements can be conducted to the fins of the heat sink quickly. The fan unit guides the outside air to the heat sink and the choke coils through the air inlets, and the heat is smoothly expelled out of the casing through the air outlets of the casing. The power inverter in a high density configuration still has a good heat dissipation effect.