Abstract: The alloys with various Mo content TiMo_x（x=0.03, 0.13, 0.25, 0.50, 1.00, Mo/Ti）were prepared with electromagnetic levitation technique. The alloys after activation react rapidly with H-D gas mixture (D%=50%), the composition of the mixture in equilibrium of isotope exchange was determined using a mass-spectroscopy. H-D separation factor α _(H-D) is defined as (D/H)_s/(D/H)_g, in which (D/H)s refers to the ratio of D and H content in solid phase, and (D/H)g refers to the ratio of D and H content in gas phase. The results show that at 20℃, x = 0.03 ～ 1.00,α _(H-D) >1.00, D prefers to stay at solid phase, and the preference becomes stronger as the Mo content increases, with α _(H-D) rising from 1.04 to 1.27. α _(H-D) keeps nearly unvaried when x=0.50～1.00. α _(H-D) ≈1.00 when x=0.03, namely TiMo_0.03 hydride shows zero effect, through previous TG-DSC analysis results, the hydride contains TiH₂ with negative effect, and Ti-Mo hydrides with positive effect, so it is the total effect of the two hydrides with opposite effect. From the relationship between the Mo content andα _(H-D) H atom prefers to take 4Ti tetrahedral interstice, whereas D atom tends to take 3Ti1Mo position in which the energy level is higher than that of 4Ti position.