Corrosion　reduces　cross-section　area　of　rebar　and　bond　between　the　rebar　and　concrete,　which　leads　to　the　degradation　of　durability　of　structure.　In　this　study,　a　three-dimensional　mesoscopic　numerical　analysis　model　was　established　to　explore　influence　of　localized　corrosion　on　behavior　of　single-way　RC　slab.　In　the　model,　concrete　was　considered　as　a　tri-phase　composite　consisted　of　coarse　aggregate　particles,　mortar　matrix　and　interface　transition　zones　(ITZs).　The　effect　of　corrosion　was　simulated　by　reducing　cross-section　area　of　rebar　and　bond.　Localized　corrosion　of　reinforcement　was　taken　into　account　and　non-linear　spring　element　was　adopted　to　describe　interaction　between　concrete　and　reinforcement.　The　simulation　results　for　corrosion　RC　slab　are　in　good　agreement　with　test　result　in　terms　of　ultimate　flexural　capacity　and　displacement.　On　this　basis,　the　flexural　behavior　of　corroded　single-way　RC　slab　under　fourth-point　bending　condition　was　simulated　and　analyzed　whilst　the　influence　of　corrosion　level,　concrete　strength,　rebar　type　and　diameter　was　investigated.　Simulation　results　indicate　that　flexural　bearing　capacity　of　corroded　RC　slab　increases　when　reinforcement　was　minor　corroded　and　decreases　for　a　further　increasing　corrosion　level.　The　effect　of　concrete　strength　on　bearing　capacity　of　slab　is　insignificant　with　the　increase　of　corrosion　level.　The　RC　slabs　with　plain　rebar　break　in　brittle　failure　when　corrosion　level　is　over　7.5%.　However,　slab　with　deformed　rebar　fail　in　a　ductile　pattern　in　this　case.　Under　fourth-point　bending　condition,　energy　dissipation　of　RC　slabs　with　larger　reinforcement　ratio　decreases　faster.　The　influence　of　reinforcement　ratio　and　bond　at　rebar-concrete　interface　caused　by　the　variation　of　rebar　diameter　is　still　significant　when　the　rebar　is　corroded.