Abstract: The high-energy laser (HEL) system proposed by General Atomics Aeronautical System, Inc. (GA-ASI) has been developed to the third generation system, which supported by high energy liquid laser area defense system (HELLADS) program and approved by U.S. government recently. Firstly, HELLADS program is reviewed. Some information, such as background, development phases, funds, relative technology developments and so on, is introduced. Secondly, system structure, technical route, pumping mode, technical characteristics and performance indexs of HEL of GA-ASI are studied in detail. Compact lithium ion battery is used as power of the third generation of HEL. The output power is 75kW, beam quality is β < 2, electrical to optical efficiency is nearly 30%, module size is 1.3m×0.4m×0.5m, weight/power ratio is 4kg/kW and continuous running time is more than 30s. The third generation of HEL is suitable for installation on all kinds of small tactical platform. Finally, the technical approach to amplify output power calibration of the laser is reviewed, and the future development direction of the laser is discussed.