The　hybrid-induced　photogating　effect　using　colloidal　quantum　dots　is　usually　utilized　to　optimize　the　performance　of　2D-based　photodetectors,　where　the　2D　material　is　usually　black　phosphorus,　transition　metal　dichalcogenides　or　graphene.　However,　the　method　of　integrating　a　single-layer　light　absorber　material　with　2D　materials　for　increasing　the　photoresponse　has　suffered　from　limited　depletion　width　so　it　can　hardly　achieve　our　desired　application.　Here,　we　proposed　a　hybrid　BP/lead　sulfide　quantum　dot　photodetector　with　a　cascade-type　energy　band　structure,　which　can　greatly　improve　the　performance　of　this　photodetector　compared　with　a　single-layer　absorber.　This　device　can　display　a　high　responsivity　of　1.1　x　10(7)　A　W-1,　a　high　detectivity　of　1.75　x　10(15)　Jones,　and　a　low　noise　equivalent　power　of　4.3　x　10(-7)　pW　Hz(-1/2)　simultaneously.　These　results　indicate　that　a　cascade-type　energy　band　structure　is　not　only　able　to　effectively　enhance　the　performance　of　the　hybrid　BP/lead　sulfide　quantum　dot　photodetector　but　also　has　great　potential　for　wide　application　in　other　2D　material-based　optoelectronic　devices.