Abstract: The Ti-6 Ni-3 Mo-1 Sn alloy ingot, an advanced sensor packaging material, was synthesized by vacuum consumable electrode arc-melting(VAR).The influence of the solid solution reaction(or arc melting) temperature and ageing on the microstructures, phases and mechanical behavior was investigated with scanning electron microscopy, transmission electron microscopy and mechanical probes.The results show that the arc-melting temperature had a major impact.Specifically, as the arc melting temperature increased, the tensile-strength, yield-strength and elongation-ratio of the aged alloy changed in an increase-decrease mode, peaking at 700℃ to 1268 MPa, 1192 MPa and 5.62%,respectively; the highly dispersed primary α-phased grains, formed in melting at 700℃,grew and turned into larger β-phased gains.Quite a few micro-pores with a fairly wide size-distribution were observed on the fractured surfaces of the aged alloy arc melted below 700℃;and the brittle-fracture accounted for the fracture mechanism.