Previous　studies　have　explored　the　effect　of　differing　heat　and　relative　humidity　(RH)　environments　on　the　performance　of　multiple　anaerobic　high-intensity　interval　training　(HIIT).　Still,　its　impact　on　physiological　responses　and　performance　following　aerobic　HIIT　has　not　been　well　studied.　This　study　examined　the　effects　of　differing　RH　environments　on　physiological　responses　and　performance　in　college　football　players　following　HIIT.　Twelve　college　football　completed　HIIT　under　four　different　environmental　conditions:　(1)　25　°C/20%　RH　(Control　group);　(2)　35　°C/20%　RH　(H20　group);　(3)　35　°C/40%　RH　(H40　group);　(4)　35　°C/80%　RH　(H80　group).　The　heart　rate　(HR),　mean　arterial　pressure　(MAP),　lactate,　tympanic　temperature　(TT),　skin　temperature　(TS),　thermal　sensation　(TS),　and　rating　of　perceived　exertion　(RPE)　were　recorded　continuously　throughout　the　exercise.　The　heart　rate　variability　(HRV):　including　root　mean　squared　differences　of　the　standard　deviation　(RMSSD)、standard　deviation　differences　of　the　standard　deviation　(SDNN)、high　frequency　(HF),　low　frequency　(LF),　squat　jump　height　(SJH),　cycling　time　to　exhaustion　(TTE),　and　sweat　rate　(SR)　were　monitored　pre-exercise　and　post-exercise.　The　HR,　MAP,　lactate,　TT,　Ts,　TS,　and　RPE　in　the　4　groups　showed　a　trend　of　rapid　increase,　then　decreased　gradually.　There　was　no　significant　difference　in　HR,　MAP,　TT,　or　RPE　between　the　4　groups　at　the　same　time　point　(p　＞　0.05),　in　addition　to　this,　when　compared　to　the　C　group,　the　lactate,　Ts,　TS　in　the　other　3　groups　significant　differences　were　observed　at　the　corresponding　time　points　(p　＜　0.05).　The　RMSSD,　SDNN,　HF,　and　LF　levels　in　the　4　groups　before　exercise　were　not　significantly　different.　The　RMSSD　and　HF　in　the　H40　and　H80　groups　were　significantly　decreased　and　other　HRV　indicators　showed　no　significant　difference　after　exercise.　In　sports　performance　measurement,　the　SJH　and　TTE　were　significantly　decreased,　but　there　was　no　significant　difference　in　the　4　groups.　The　SR　was　no　significant　difference　in　the　4　groups　after　exercise.　In　conclusion,　heat　and　humidity　environments　elicited　generally　greater　physiological　effects　compared　with　the　normal　environment　but　did　not　affect　sports　performance　in　college　football　players.　©　The　Author(s)　2024.