Abstract: The vacuum brazing and solution+aging treatment of the Al-Mg-Si aluminum alloy radiators were studied.Firstly, the solidus temperature of the base material and the liquidus temperature of the brazer were determined by thermal analysis, then the vacuum brazing parameters were determined.Secondly, the phases of the brazer, base metal and the vacuum brazing weld were tested by X-ray diffractometer.Finally, the microstructure and the mechanical properties of the weld treated by different process were analyzed.The results show that high quality weld can be acquired under vacuum brazing process of 608 ℃/70 min, and there are no defects such as crack, hole, dissolution.With the increase of solution temperature, the grain size and primary phase's solubility of the weld increase.The appropriate heat treatment process of the weld is 530 ℃/3 h and 150 ℃/5 h.Under solution treatment of 550 ℃/5 h, the primary phase's solubility of the base metal is maximum, and under the aging treatment of 150 ℃for 9 h, a mass of needle-shape β" and rod-shape β' phase appear.The optimal heat treatment process of the base metal is 550 ℃/5 h+150 ℃/9 h.By optimization and comparison, the heat treatment process of the radiator is 540 ℃/4 h and 150 ℃/6 h, under the process the mechanical properties of the weld and the base metal can be guaranteed.