Abstract: Spray formed hypereutectic Al-Si-Cu-Mg alloy has superior wear resistance, low thermal expansion coefficient and density and high thermal conductivity. The vacuum brazing method was used to braze Al-25Si-4Mg-1Cu alloy with Zn as the interlayer. The interfacial microstructure and shear strength of Al-25Si-4Cu-1Mg joints were investigated at different brazing temperatures. The results show that the metallurgical combination between Al-Si-Mg-Cu alloys is mainly realized by Zn-Al solid solution, primary Si and α-Al phases. With the increase of the brazing temperature, the width of the brazing seam has not changed significantly, but the composition of the brazing seam changes significantly. When the temperature rises from 400 ℃ to 415℃, the content of Al element in the brazing seam increases, the amount of Zn-Al solid solution is significantly reduced, and a large amount of α-Al appears. The primary Si particles gradually move from the interface between base material and brazing seam to the center of the brazing seam, the phase composition of the brazing seam is close to that of the base material, thereby increasing the shear strength of the joint. When the temperature reaches 415 ℃, the maximum shear strength of the joint reaches 44.68 MPa.