Si3N4 Ceramics were bonded by brazing with bonding materials composed of Ag-Cu-Ti foils and Ti/Ni/Ti multi-interlayer,which enhance the joint strength by in situ reaction occurred while brazing.Ni-Ti-Cu intermetallic compounds were observed in the joints by X-ray analysis.The intermetallic particles are homogeneously distributed in the matrix so they contribute to the joint strength.The distribution of intermetallic compounds and the status of interfacial reaction layer have obvious effect on the joint strength.The interfacial reaction layer has a two-layer structure,and the formation of which has three steps.