TiO-precipitate and H atom are crucial factors for degradation of mechanical properties in vanadium alloys under irradiation environment. Herein, the behaviors of H atom at TiO/V interface are systemically studied by first principles calculations to elucidate the influence of TiO-precipitate on the H bubble formation. H atom prefers to dissolve in octahedral interstitial site (OIS2) with smaller lattice distortion and stronger bonds. The electronic interaction between H atom near monovacancy at the interface and surrounding atoms is enhanced with the existence of the TiO-precipitate. The capture of four H atoms in monovacancy is thermodynamically optimal, and the electronic action mainly contributes to the total trapping energy by monovacancy. The total trapping energy by multi-vacancy clusters is independent of the number of vacancies. H atoms trapped by vacancies cannot form H2 molecule at TiO/V interface. Our work can provide theoretical guidance for further understanding the H bubbles formation in vanadium alloys.