The invention provides a high efficiency power amplifier comprising a metal shell, wherein reinforcement components are arranged at four corners of the metal shell; each reinforcement component comprises a connection plate, a press plate, an outer-layer corner plate and an inner-layer corner plate; each connection plate is L-shaped, two ends of the connection plate are respectively connected with two end faces of each corner of the metal shell, and two ends of the press plate are respectively connected with the outer sides of the two end faces; each outer-layer corner plate is L-shaped and provided with an arc angle at the middle portion, edges of two ends of the outer-layer corner plate are respectively connected with outer side faces of each corner of the metal shell, and the outer-layer corner plate covers the corresponding press plate; each inner-layer corner plate is L-shaped, two sides of the inner-layer corner plate are respectively connected with inner side faces of each corner of the metal shell; a bottom plate is provided with an opening where a radiator and a heat dissipation plate are arranged, the radiator is provided with rectangular grooves in vertical and horizontal directions, the heat dissipation plate comprises a cooling plate and cooling fins directly in close contact with the lower end of the radiator, and heat transmission copper tubes are arranged on the cooling plate. The high efficiency power amplifier provided by the invention can fully dissipate heat.