With　the　development　of　cloud　computing,　a　growing　number　of　users　use　the　cloud　to　store　their　sensitive　data.　To　protect　privacy,　users　often　encrypt　their　data　before　outsourcing.　Searchable　Symmetric　Encryption　(SSE)　enables　users　to　retrieve　their　encrypted　data.　Most　prior　SSE　schemes　did　not　focus　on　malicious　servers,　and　users　could　not　confirm　the　correctness　of　the　search　results.　Blockchain-based　SSE　schemes　show　the　potential　to　solve　this　problem.　However,　the　expensive　nature　of　storage　overhead　on　the　blockchain　presents　an　obstacle　to　the　implementation　of　these　schemes.　In　this　paper,　we　propose　a　lightweight　blockchain-based　searchable　symmetric　encryption　scheme　that　reduces　the　space　cost　in　the　scheme　by　improving　the　data　structure　of　the　encrypted　index　and　ensuring　efficient　data　retrieval.　Experiment　results　demonstrate　the　practicability　of　our　scheme.　©　2021　IEEE.