The　continuous　methane　emission　from　the　coal　piles　is　associated　with　many　environmental　problems　and　safety　risks,　in　large　storage　facility.　The　methane　emission　parameters　of　coal　piles　and　the　concentration　distribution　characteristics　of　methane,　which　are　the　basis　of　ventilation　design,　are　rarely　reported　in　large　storage　facilities.　In　this　study,　based　on　the　mass-transfer　diffusion　theory,　desorption-concentration　gradient　method　for　deter-mining　methane　emission　parameters　of　coal　piles　in　large　facilities　is　proposed.　In　this　method,　firstly,　the　coal　pile　methane　diffusion　coefficient　was　deduced　by　conducting　the　coal　particles　absorption-desorption　experi-ments　and　the　particle-size　distribution.　Then,　combing　the　diffusion　coefficient　and　methane　concentration　-gradient　on　the　coal　pile　surface,　the　coal　pile　methane　diffusion　flux　was　calculated.　Further,　when　methane　diffusion　flux　was　utilized　as　the　source　item　for　CFD　calculations,　the　results　were　consistent　with　the　onsite　measured　values,　which　demonstrated　the　accuracy　of　this　method.　The　CFD　simulation　results　show　that　methane　has　diffusion　characteristics　that　adhere　upward　along　the　slope　of　the　coal　pile　and　converge　on　the　coal　ridge.　The　methane　flow　reaches　the　dome　upwards,　where　a　higher　concentration　is　formed.　Both　the　coal　pile　volume　and　the　methane　diffusion　flux　will　affect　the　concentration　distribution　of　methane　in　large　storage　facility.　For　a　larger　diffusion　flux,　the　explosion　limit　will　be　exceeded,　and　measures　need　to　be　taken　to　eliminate　the　safety　risk.　These　findings　provide　principal　data　and　analysis　guide　for　optimized　design　of　ventilation　performance　in　closed　industrial　building.