Abstract: W/Cu interface, as an important material interface of divertor in fusion reactor, is a strong trap of the hydrogen isotopes under high heat flux and strong neutron irradiation. Ab initio calculation was used to investigate the interaction of hydrogen atom and point defect in W/Cu interface, the behavior of hydrogen atom retention and point defect formation, the priority position of hydrogen atom and the mechanism of interaction of hydrogen atom and vacancy. The result shows that hydrogen atoms prefer to exist among the interface and copper lattice steadily. As for vacancy, vacancy copper near the interface is unstable to move to the upper face, however, vacancy tungsten almost presents a stable existence phenomenon. Compared with vacancy copper, vacancy tungsten has the stronger ability to attract hydrogen atom. Meanwhile, the existence of hydrogen atom would suppress the migration of vacancy copper, and it may cause the bubble of hydrogen.