Abstract: With the development of military electronic device and microwave device, high power density device is more widely used in military electronic equipment. The power density of these devices is getting higher and higher, therefore the demands of heat dissipation increase. The article discusses a forced liquid-cooling heat dissipation technology based on vapor chamber for high heat flux components of missile-borne radar. Transient temperature distribution at 120 s and steady temperature distribution of the thermal model are simulated. Analysis result shows that the high heat flux chips could work well. The working condition requirements and the uninterrupted test requirements of the radar guidance assembly can be guaranteed.