With　the　continuous　development　of　the　Internet　of　Things,　more　and　more　social　sectors　and　smart　devices　are　connected　to　the　Internet　of　Things.　This　has　led　to　a　spurt　of　data　growth　and　posed　challenges　to　data　security.　To　solve　this　problem,　the　Internet　of　Things　needs　a　more　secure　and　efficient　storage　method.　Nowadays,　one　of　the　most　important　creative　technological　advancements　that　plays　a　significant　role　in　the　professional　world　is　blockchain　technology.　And　Both　academia　and　industry　attach　great　importance　to　the　research　of　blockchain　application　technology.　Some　scholars　believe　that　the　blockchain　itself　is　a　secure　distributed　database.　So,　Blockchain　is　also　considered　a　safe　way　to　store　data.　In　this　paper,　we　introduce　blockchain　into　the　Internet　of　Things　to　ensure　the　security　of　Internet　of　Things　data.　At　the　same　time,　we　have　solved　the　problem　of　quantifying　the　degree　of　blockchain　decentralization,　which　provides　conditions　for　system　optimization.　After　that,　we　proposed　a　system　optimization　model　based　on　deep　reinforcement　learning　to　dynamically　adjust　system　parameters.　The　simulation　results　show　that　the　decentralization　of　the　blockchain　and　the　security　of　the　system　are　guaranteed,　and　the　throughput　of　the　system　has　been　improved.　©　2022,　The　Author(s),　under　exclusive　license　to　Springer　Nature　Switzerland　AG.