High power diode lasers (HPDLs) have been applied in more and more fields, such as material processing, pumping of solid-state lasers and fiber lasers, medical therapy. With the improvement of output power, efficiency and reliability, thermal management has been one of most critical issue for HPDLs. The junction temperature of a diode laser package has critical effects on laser characteristics, affecting wavelength, output power, threshold current, slope efficiency, and operating lifetime. Lower junction temperature is an effective means to achieve high output power and high electrooptical conversion efficiency of diode lasers. In recent years, high-power diode lasers operated at cryogenic temperature have attracted academic interests. Herein, high power diode lasers suitable at cryogenic temperature and a measurement setup at cryogenic temperature have been developed. The optical-electrical performance of microchannel cooled high power diode lasers from 0℃ ~ -60℃ have been studied theoretically and experimentally. The output power increases 18% and the conversion efficiency increases 6.3% from 0 ºC to -60 ºC. The high diode laser bars operated at cryogenic will be applied in pumping high energy lasers in the future.