Studies　on　hydrogen　leakage　have　mainly　focused　on　the　influences　of　location　and　geometrical　configuration　on　the　distribution　of　the　hydrogen　in　various　spaces.　The　present　study　developed　a　simplified　model　for　the　leakage　diffusion　of　hydrogen　in　an　enclosed　cuboid　space　with　two　vents,　at　the　top　and　at　the　bottom,　respectively.　The　effect　of　different　leakage　positions　on　the　diffusion　of　the　hydrogen　was　analyzed.　The　results　showed　that　when　hydrogen　diffused　vertically　from　the　bottom　to　the　top　of　the　space,　the　farther　the　leakage　position　was　from　the　vent　on　the　side　wall,　the　more　hydrogen　accumulated.　When　the　hydrogen　leaked　in　the　vertical　direction　from　the　floor,　the　distance　between　the　leakage　position　and　the　bottom　vent　had　little　effect　on　the　horizontal　diffusion　speed　of　the　hydrogen　at　the　top　of　the　space.　The　diffusion　speed　for　the　leakage　in　the　horizontal　direction　was　faster　than　that　in　the　vertical　direction.　When　the　hydrogen　leaked　in　the　horizontal　direction　from　the　side　wall,　the　height　of　the　leakage　had　little　effect　on　the　horizontal　diffusion　speed　of　the　hydrogen　at　the　top　of　the　space.　Stratification　occurred　for　models　set　up　in　the　present　study　whenever　the　envelope　of　1%　mole　fraction,　or　4%　mole　fraction,　of　hydrogen　extended　to　the　whole　ceiling.