W-Cu composite and 18-8 stainless steel were vacuum brazed with an improved Ni-based filler metal, with varying Ti content. The microstructure, element distribution, phase composition, and fracture mechanism of the brazed joints were investigated. The improved NiCrSiBFe-Ti quench filler metal showed good wettability on the W-Cu composite and 18-8 stainless steel. Enhanced diffusion and metallurgical reactions between the filler metal and base metal were observed. The addition of Ti not only optimized the structure, but also reduced the formation of brittle intermetallic compounds, which is important for significantly improving the brazed-joint strength. The highest brazed-joint shear strength (381 MPa) was observed when the Ti content was 1.6％.