Effect of Minor Si and Ag additions on glass-forming ability (GFA) of the base Ti44Cu38.9Co4Zr6Sn2Be5.1 (at. %) alloy are studied. (Ti44Cu38.9Co4Zr6Sn2Be5.1)100-xRx (R = Si, Ag, x=0, 1, 2, 3 at. %) metallic glasses are formed by splat-quenching and copper mold suction casting. It is found that the minor Si and Ag additions enhance the glass-forming ability of Ti44Cu38.9Co4Zr6Sn2Be5.1 greatly. The maximum size of fully amorphous structure is increased from 4 mm for base alloy to be larger than 6 mm for alloys containing 1-2 at. % Si/Ag, while Si/Ag more than 2 at. % additions decrease the GFA.