The　exploitation　of　gas　therapy　platforms　holds　great　promise　as　a　＂green＂　approach　for　selective　cancer　therapy,　however,　it　is　often　associated　with　some　challenges,　such　as　uncontrolled　or　insufficient　gas　generation　and　unclear　therapeutic　mechanisms.　In　this　work,　a　gas　therapy　approach　based　on　near-infrared　(NIR)　light-triggered　sulfur　dioxide　(SO2)　generation　was　developed,　and　the　therapeutic　mechanism　as　well　as　in　vivo　antitumor　therapeutic　efficacy　was　demonstrated.　A　SO2　prodrug-loaded　rattle-structured　upconversion@silica　nanoparticles　(RUCSNs)　was　constructed　to　enable　high　loading　capacity　without　obvious　leakage　and　to　convert　NIR　light　into　ultraviolet　light　so　as　to　activate　the　prodrug　for　SO2　generation.　In　addition,　SO2　prodrug-loaded　RUCSNs　showed　high　cell　uptake,　good　biocompatibility,　intracellular　tracking　ability,　and　high　NIR　light-triggered　cytotoxicity.　Furthermore,　the　cytotoxic　SO2　was　found　to　induce　cell　apoptosis　accompanied　by　the　increase　of　intracellular　reactive　oxygen　species　levels　and　the　damage　of　nuclear　DNA.　Moreover,　efficient　inhibition　of　tumor　growth　was　achieved,　associated　with　significantly　prolonged　survival　of　mice.　Such　NIR　light-triggered　SO2　therapy　may　provide　an　effective　strategy　to　stimulate　further　development　of　synergistic　cancer　therapy　platforms.　©　2019　American　Chemical　Society.