The unusual glass-forming ability (GFA) of the Zr₄₈Cu₃₆Ag₈Al₈ alloy and the high ductility of the Zr₄₈Cu₃₆Ag₈Al₈ metallic glass-matrix composites containing Ta powder were reported. The bulk metallic glass rod with a diameter of 25 mm was successfully synthesized using copper mold casting for the Zr₄₈Cu₃₆Ag₈Al₈ alloy. High GFA of this alloy was found to be related to a large supercooled liquid region and a quaternary eutectic point with low melting temperature. The bulk metallic glass matrix composites were prepared by introducing extra Ta particles into the Zr₄₈Cu₃₆Ag₈Al₈ melt. The composites consist of Ta particles homogenously distributed in the Zr₄₈Cu₃₆Al₈Ag₈ metallic glass matrix. The optimum content of Ta powder is 10at% for the composite with the highest plasticity, which shows a plastic strain of 31%.