Ti-3wt.%Nb(${alpha}$type), Ti-20wt.%Nb(${alpha}+{eta}$,type) and Ti-40wt.%Nb(${eta}$type) alloys were melted by vacuum are remelting. The specimens were homogenized at 1050$^{circ}C$ for 24 hr and were then hot rolled to 50% reduction. Each alloys were solution heat treated at ${eta}$ zone and ${alpha}+{eta}$, zone after homogenization, and then aged. The microstructural and hardness changes in Ti-Nb alloys with Nb contents were investigated by SEM, XRD and hardness tester. The microstructural change from equiaxied to acicular and the increase of ${eta}$ phase in Ti-Nb alloys were obtained when the Nb content increased. The higher hardness value of ${alpha}+{eta}$type alloy was obtained compared to the other alloys.