Antimony　sulfide　(Sb2S3)　is　considered　an　excellent　semiconductor　material　for　visible　light　photodetectors　(PDs)　due　to　the　non-toxicity,　stability　and　high　visible　photon　absorption　coefficient.　However,　the　deep　physical　cascade　relationship　between　Sb2S3　devices　and　key　parameters,　such　as　the　thickness,　the　doping　density,　the　defect　density,　and　the　inverse　contact　of　the　figure　of　merit,　has　not　been　thoroughly　investigated.　In　order　to　systematically　explore　the　impact　of　parameters　on　Sb2S3　device　performance,　self-powered　optoelectronic　devices　of　TiO2/Sb2S3　p-n　heterojunction　were　simulated　by　using　one-dimensional　(SCAPS-1D)　software.　Base　on　simulation,　we　learned　that　the　optimum　thickness　of　Sb2S3　is　about　400　nm,　the　donor　and　acceptor　densities　of　TiO2　and　Sb2S3　layers　are　1020　and　1016　cm-3,　respectively.　In　addition,　Au　was　chosen　as　the　back　electrode,　and　the　high-quality　Sb2S3　functional　layer　required　a　defect　density　of　less　than　1016　cm-3.　Based　on　the　guidance　of　simulation　results,　we　finally　fabricated　the　FTO/TiO2/Sb2S3/Au　self-powered　photodetectors.　Under　an　illumination　intensity　of　3　mu　W/cm2　at　530　nm,　the　responsivity　(R)　and　specific　detectivity　(D*)　of　the　device　can　be　up　to　0.357　A/W　and　5.1　x　1011　Jones,　respectively.　Particularly,　the　device　exhibits　a　fast　response　with　a　response　time　of　1.4　mu　s　and　3　dB　bandwidth　of　383　kHz.　In　this　regard,　we　constructed　a　single-pixel　scanning　imaging　system　around　the　Sb2S3　detector　and　showed　excellent　imaging　results,　which　provided　a　new　path　for　us　to　develop　a　new　type　of　visible　light　detector　and　imaging　system.