The　development　of　high-performance　hydrogen　sensors　is　considered　of　great　significance　for　the　safety　of　hydrogen　energy　and　related　industries.　The　two-dimensional　(2D)　MoS2　nanomaterials　have　exhibited　great　superiority　in　building　fast　and　reliable　room-temperature　hydrogen　sensors.　However,　their　poor　sensitivity　and　selectivity　issues　still　limit　their　wide　exploitation.　In　this　work,　nano-SnO2-modified　MoS2　thin　films　with　structure-dependent　n-p　tunable　hydrogen　response　behaviours　were　reported.　The　in-situ　scanning　Kelvin　probe　microscopy　(SKPM)　study　on　the　hydrogen　response　of　the　SnO2/MoS2　systems　revealed　the　different　reductions　in　the　surface　potential　of　SnO2　(0.38　eV)　and　MoS2　(0.26　eV)　in　a　hydrogen　environment,　which　results　in　different　variations　in　the　interface　potential　barrier　with　the　increasing　surface　coverage　of　SnO2.　As　a　result,　the　contribution　from　the　interface　effect　to　the　n-type　hydrogen　response　was　changed　from　the　positive　enhancement　to　the　negative　compensation.　The　sensor　exhibited　a　fast,　enhanced,　and　selective　n-type　hydrogen　response　with　the　SnO2　coverage　down　to　6.4%,　while　a　p-type　sensor　response　was　achieved　when　the　SnO2　coverage　increased　to　95.6%.　Such　structure-dependent　n-p　tunable　hydrogen　sensing　behaviour　can　not　only　be　utilized　for　the　sensitization　of　the　sensing　layers　but　may　also　provide　a　simple　and　cost-effective　way　for　the　modulation　of　the　response　type　of　the　sensor　composed　of　the　MoS2-based　2D　materials.　©　2023,　Science　China　Press.