In　this　paper,　the　diffusion　law　of　helium　gas　inside　composite　materials　was　obtained　through　numerical　research　and　an　experimental　approach.　The　influence　of　fiber　and　the　fiber–resin　interface　on　permeability　was　discussed　in　the　actual　numerical　model.　It　was　found　that　the　leak　rate　and　the　mass　concentration　at　the　fiber–resin　interface　were　higher　than　those　in　the　resin,　and　the　leak　rate　symmetrically　distributed　along　the　horizontal　central　line.　Meanwhile,　a　homogenized　model　for　the　leak　rate　simulation　in　carbon　fiber　composite　components　was　established,　and　its　accuracy　was　verified　through　the　experiment　and　the　actual　numerical　model.　The　simulated　result　and　the　test　data　demonstrated　that　the　leak　rate　increased　with　the　pressure　and　decreased　with　the　thickness　of　the　specimen.　©　2023　by　the　authors.