Molecular dynamics simulations were performed to investigate the nucleation and growth of helium bubble on W/Ta semi-coherent interface. It is found that misfit dislocation has a significant impact on the nucleation and growth of helium bubble. He bubble energetically prefers to nucleate at the intersections of the misfit dislocations or on some misfit dislocations. During the bubble growing process, metal interstitial atoms pushed out by the bubble are directly absorbed into nearby misfit dislocations, leading them to climb towards the Ta side; in turn, the climbed misfit dislocations induce He bubble moving away from the bimetal interface and into Ta side. Finally, the misfit dislocation effect on the bubble growth was further discussed in terms of wetting theory.