The invention discloses a converter device of an MW (Megawatt) excitation wind power unit, which comprises a converter unit cabinet, a machine side cabinet and a grid side cabinet; the converter unit cabinet comprises a rectifier unit, an inverter unit, a first centrifugal fan, a second centrifugal fan, a first water-cooled pipeline and a second water-cooled pipeline; a first IGBT (Insulated Gate Bipolar Translator) module and a first capacitance matrix in the rectifier unit are arranged on a first bottom plate; the first bottom plate and the front plate, the rear plate and a first side plate of the cabinet body form a first air duct; a second IGBT module and a second capacitance matrix in the inverter unit are arranged on a second bottom plate; the second bottom plate and the front plate, the rear plate and a second side plate of the cabinet body form a second air duct; the first bottom plate and the second bottom plate are over against each other and separated to form a gap between; the first and the second water-cooled pipelines are arranged in the gap between the first and the second bottom plates; and third water-cooled pipelines are respectively arranged in the grid side cabinet and the machine side cabinet to cool a first reactor and a second reactor. The converter device of the MW excitation wind power unit according to the embodiment of the invention has a compact structure, a small size and a good radiating effect.