With　unique　photoelectronic　properties,　perovskites　have　drawn　attention　in　photocatalysis.　However,　their　activity　and　stability　especially　in　moist　environments　is　not　appealing,　despite　it　was　demonstrated　that　the　construction　of　three-dimensional　(3D)　and　low-dimensional　counterparts　could　result　in　boosting　of　activity　and　stability,　respectively.　Here,　a　lead-free　hybrid　double　perovskite　((DETA)BiBr6/Cs2AgBiBr6,　DCABB)　was　fabricated　by　uniformly　dispersing　0D　DETABiBr(6)　(DETA(3+)　=　NH3+(CH2)(2)NH2+(CH2)(2)NH3+)　in　the　matrix　of　3D　Cs2AgBiBr6.　Benefited　from　the　passivation　of　Br　defects　and　resistance　of　water　by　DETA(3+),　the　stability　of　DCABB　improved　in　comparison　to　pristine　3D　Cs2AgBiBr6.　Moreover,　the　formation　of　DCABB　increased　the　adsorption　of　O-2　and　the　accumulation　of　photogenerated　electrons　on　the　surface　of　catalyst,　consequently　boosting　the　generation　of　active　O-center　dot(2)-　and　(OH)-O-center　dot　species.　The　DCABB　displayed　higher　photocatalytic　performance　than　its　components　in　toluene　selective　oxidation　under　visible　light　illumination,　achieving　a　toluene　conversion　of　up　to　100　%.