The (Ti_0.46Cu_0.14Zr_0.27Ni_0.13)_1-xSi_x amorphous filler metal was prepared by arc melting and fast-cooling melt-spinning technologies, and the effect of a certain amount of Si added to the filler metal on its amorphous forming ability was studied. The results show that the filler metal presented the strongest amorphous forming ability when the additive Si reached 0.5%; its wetting area was 3.06 cm₂,its supercooled liquid phase region width (?T_x) ?T_x=56 ℃,its reduced glass transition temperature (T_rg) T_rg=0.5387, and its liquidus temperature was 949 ℃. The vacuum brazing was done for SiC and TC4 using this amorphous alloy as the filler metal, and the shear strength of brazed joint was 80 MPa. The amorphous forming ability of filler metal was improved with addition of Si to the filler metal.