Abstract: As an efficient heat exchanger, the cold plate ensures the long-term stable operation of the T/R module of radar. With increase of heat flux of the T/R module, the cold plate manufactured with traditional manufacturing techniques can’t meet the high heat dissipation requirement, while the micro/mini-channel cold plate gets more and more attention because of its good heat transfer property. In this paper, taking the cold plate in an active phased array radar as research object, the cooling capacity and manufacturing cost of the micro/mini-channel cold plates and traditional cold plate with circular channel are compared and thermal simulation design is carried out. The results show that the mini-channel cold plate with rectangular section is the most suitable one. Then the comparison result shows that the brazing in nitrogen atmosphere is more suitable than diffusion welding as the welding method of the mini-channel cold plate. At last, the feasibility of the welding procedure is verified by various inspection after welding.