Single-layer　graphene　has　been　proved　to　be　an　ideal　material　for　broadband　high-speed　photodetector.　However,　the　pure　graphene　photodetector　photoresponsivity　is　limited　to　tens　of　mA　/W　by　the　low　optical　absorption　and　short　exciton　life　of　graphene.　When　higher　responsivity　is　needed,　the　graphene　layer　needs　to　be　coupled　with　other　materials,　e.g.,　Titanium　Dioxide　(TiO2).　Conventional　TiO2　recipes　require　either　solution　or　high　temperature　which　tends　to　destruct　the　graphene　layer.　In　this　work,　TiO2　is　synthesized　by　oxygen　plasma　treating　Ti　film.　This　novel　synthesis　route　of　TiO2　avoids　defects　introduced　by　the　conventional　recipes.　The　hybrid　device　shows　a　high　photoresponsivity　of　similar　to　179　A　/W,　a　fast　response　time　of　similar　to　20　ms　and　a　specific　detectivity　of　similar　to　9.12　x　10　(9)　Jones　with　the　incident　light　intensity　of　sub-microwatt.　Under　the　illumination,　the　photon　absorption　in　graphene　creates　electron-hole　pairs,　which　were　separated　at　TiO2/graphene　interface　by　an　internal　electric　field　and　corresponding　electrons　transfer　from　the　graphene　to　TiO2　layer.　The　high　photoresponsivity　is　attributed　to　the　long　lifetime　of　the　photoexcited　charge　carriers　caused　by　a　built-in　field　at　the　interface　of　TiO2/graphene.　Our　research　provides　an　effective　method　to　improve　the　photoresponse　of　the　graphene-based　photodetector.　In　addition,　our　TiO2　recipe　could　be　applied　in　the　fabrication　of　other　electronic　devices　where　solution　or　high　temperature　processes　are　difficult.