A high efficiency supersonic plasma spray system (HEPJet) was successfully developed with a maximum power of 80 kW and a maximum working gas flow of 6 m3/h. It can be used to spray metallic, carbide and oxide powders. The supersonic plasma spraying gun has a single-anode, internal feeding structure. The development of 80 kW inverse power supply with 20 kHz PWM IGBT circuit solved the problems of high output voltage, high output current and strong interference of high frequency. The production cost of this system is only equivalent to that of ordinary plasma systems. The average velocity of Al2O3 particles in the plasma jet measured with a Oseir Spray Watch system reached 740m/s, and the coatings show high quality, good bonding strength and low porosity. The Co/WC coatings deposited by HEP Jet avoided the degradation from WC to W2C which should be attributed to the strong adjustability of the system for jet temperature and jet velocity.