Floating　gate　transistor　photomemory　(FGTPM)　has　been　regarded　as　one　of　the　most　prospective　nonvolatile　photomemory　devices　because　of　its　compatibility　with　transistor-based　circuits,　nondestructive　reading,　and　multilevel　storage.　Until　now,　owing　to　the　excellent　photoelectric　properties,　lead-based　perovskite　nanocrystals　(PNCs)　have　been　applied　in　most　of　the　perovskite-based　FGTPM　devices　and　embedded　in　the　polymer　matrix　as　the　charge　trapping　layer.　However,　the　polymer　matrix　and　its　solvent　would　degrade　the　structure　of　the　PNCs,　resulting　in　the　loss　of　their　unique　photoresponse　ability.　In　addition,　lead-based　perovskites　have　environmental　unfriendliness　and　poor　stability.　Hence,　a　novel　nonvolatile　FGTPM　based　on　oligomeric　silica　(OS)　wrapped　lead-free　double　perovskite　Cs2AgBiBr6　NCs　was　demonstrated　for　the　first　time.　Acting　synchronously　as　the　protection　layer　for　the　discrete　Cs2AgBiBr6　NCs　and　charge　tunneling　layer　for　the　FGTPM　device,　the　OS　layer　can　achieve　controllable　thickness　by　adjusting　the　process　parameters,　leading　to　an　adjustment　of　storage　properties　with　a　larger　memory　window　(58　V).　Owing　to　the　excellent　photoresponse　ability　of　the　Cs2AgBiBr6@OS　composite　layer,　the　FGTPM　device　exhibited　high-performance　with　repeatable　multilevel　nonvolatile　photomemory　and　precise　photoresponse　ability　of　wavelength/time/power-dependent　photoirradiation　without　extra　gate　biasing.