Due　to　the　urgent　need　for　reducing　carbon　emissions,　an　increasing　number　of　pumped　storage　power　stations　have　been　constructed　and　used　considering　its　obvious　advantages　of　energy　saving.　However,　relevant　design　guidance　and　technical　research　failed　to　meet　the　development　demand.　There　is　only　a　small　number　of　studies　focusing　on　the　prediction　and　evaluation　of　ventilation　system　in　single-story　stations,　however,　little　on　the　integral　connected　plant　floors.　Thus,　it　is　significant　to　study　safety　operation　technology　of　deep　underground　pumped　storage　power　stations,　especially　in　terms　of　thermal　and　humidity　environment.　A　reduced-scale　(1/30)　model　based　on　an　engineering　project　was　set　up,　and　numerical　simulations　were　carried　out　to　study　the　temperature　and　velocity　distribution　in　the　large　underground　space　under　the　summer　design　condition　(L=21.1×104m3/s,　T=19℃,　Q=997KW).　Results　show　that　the　temperature　on　the　right　side　of　the　powerhouse　is　slightly　higher　than　that　on　the　left　side,　and　the　gap　is　approximately　from　1℃　to　4℃.　Moreover,　local　overheating　may　occur　in　some　places.　The　side　air　supply　velocity　and　location　should　be　paid　more　attention　to　in　designing　air　distribution.　©　The　Authors,　published　by　EDP　Sciences.　This　is　an　open　access　article　distributed　under　the　terms　of　the　Creative　Commons　Attribution　License　4.0　(http://creativecommons.org/licenses/by/4.0/)