The　understanding　of　hydrogen　embrittlement　(HE)　is　of　significant　importance　and　fundamental　interest　owing　to　its　negative　effects　on　industrial　metallic　materials.　The　effect　of　solute　H　on　the　void　coalescence　and　growth　needs　to　be　clarified.　Using　molecular　dynamics　simulation,　the　evolution　of　preexisting　nano　voids　is　studied　in　the　presence　of　H　atoms.　As　the　per　unit　area　concentration　of　trapped　H　atom　on　void　surface　reaches　0.45　/angstrom(2),　the　movement　of　void　is　observed.　It　proceeds　along　with　the　interdiffusion　of　H　and　Fe　atoms　around　the　voids.　Strain-mediated　diffusion　of　H　atoms　from　void　surface　to　the　zone　between　nearest　voids　occurs　at　first.　Then　the　Fe　atoms　are　affected　by　migrated　H　and　diffuse　in　the　opposite　direction　following　the　principle　of　energy　minimization.　Such　mechanism　can　help　us　understand　the　formation　of　high　pressure　bubble　at　nano　scale.　Based　on　this　useful　information,　some　methods　could　be　obtained　to　prevent　the　growth　of　voids　further,　such　as　strengthening　the　stability　of　metal　lattice　around　voids　by　dopant　etc.