Abstract: Eutectic soldering technology of high power microwave chip is studied using automatic soldering system in this paper. Influence factors for eutectic soldering area ratio, such as solder presetting on heat sink, temperature curves, nitrogen protection atmosphere and friction times, are analyzed respectively. High power microwave chip eutectic soldering module with good soldering area ratio is obtained at last by presetting solder on MoCu heat sink, using optimized soldering temperature curves, applying a certain flow rate of nitrogen protection atmosphere and using appropriate friction times. Soldering position precision can be controlled within(25±5) μm. Thermal cycle test of the high power module after soldering is accomplished and shear test of the microwave chip is carried out. The results indicate that the shear force of the solder joints meets the demands of GJB 548B—2005, and the high power microwave chip eutectic soldering module obtained by using the optimized process parameters has high reliability.