The effect of tin (Sn) addition on the glass forming ability (GFA) and mechanical properties of the Ni-Nb-Zr ternary alloy system has been studied. The addition of Sn improves the GFA; Ni61Nb35.5-xZr3.5Snx (in at.%) alloys with x=1 can be cast into amorphous samples at least 3 mm in diameter using a copper mold injection-casting method. The critical size for glass formation decreases to 2 mm when x=5 because Ni2SnZr phase precipitates readily. The addition of Sn is also effective in enhancing the stability of the supercooled liquid; a maximum supercooled liquid region of 48 K was attained for the Ni61Nb30.5Zr3.5Sn5 alloy. Compression tests reveal that the Ni61Nb33.5Zr3.5Sn2 alloy possesses the best mechanical properties,with yield strength～3180 MPa,fracture strength～3390 MPa and plastic strain ～1.3%. The fracture surfaces examined by scanning electron microscopy indicate that the alloys have a transition from ductility to brittleness in fracture behavior. The combination of high GFA,high thermal stability,high strength and compressive plasticity makes these alloys potentially attractive for engineering applications. The effect of tin (Sn) addition on the glass forming ability (GFA) and mechanical properties of the Ni-Nb-Zr ternary alloy system has been studied. The addition of Sn improves the GFA; Ni61Nb35.5-xZr3.5Snx (in at.%) alloys with x = 1 can be cast into amorphous samples at least 3 mm in diameter using a copper mold injection-casting method. The critical size for glass formation decreases to 2 mm when x = 5 because Ni2SnZr phase precipitates readily. The addition of Sn is also effective in enhancing the stability of the supercooled liquid; a maximum supercooled liquid region of 48 K was attained for the Ni61Nb30.5Zr3.5Sn5 alloy. Compression tests reveal that the Ni61Nb33.5Zr3.5Sn2 alloy possesses the best mechanical properties, with yield strength ~ 3180 MPa, fracture strength ~ 3390 MPa and plastic strain ~ 1.3%. The fracture surfaces examined by scanning electron microscopy indicate that the alloys have a transition from ductility to brittleness in fracture behavior. The combination of high GFA, high thermal stability, high strength and compressive plasticity makes these alloys potentially attractive for engineering applications.