In　this　paper,　numerical　simulation　is　carried　out　to　study　the　flow　and　heat　transfer　of　pulsating　flow　in　30°　45°　60°　and　90°　ribbed　channels　(AR　=　2).　Turbulence　model　validation　has　been　conducted　for　steady　flow　only,　indicating　that　SST　k-ω　model　predicts　heat　transfer　in　ribbed　channels　fairly　well.　The　secondary　flows　and　Nu　distributions　in　ribbed　channels　are　investigated　for　both　steady　flow　and　pulsating　flow.　Numerical　results　indicate　that　pulsating　flow　affects　longitudinal　secondary　flow　and　transverse　secondary　flow　in　quite　different　ways.　The　time-averaged　Nu　on　ribbed　surface　of　pulsating　flow　is　significantly　higher　than　that　of　steady　flow　in　most　cases,　especially　for　90°　rib　case.　There　is　an　optimal　frequency　for　each　channel　to　achieve　the　best　heat　transfer.　In　addition,　increasing　pulsation　amplitude　and　Re　will　noticeably　promote　heat　transfer　for　all　the　cases.　Though　pulsating　flow　introduces　large　pressure　loss,　considerable　improvement　of　thermal　performance　will　be　achieved　at　high　Re.　The　90°　ribbed　channel　shows　distinguished　characteristics　with　pulsating　flow,　which　gains　an　increment　of　39%　in　overall　thermal　performance　parameter　at　Re　=　40,000,　f　=　150　Hz　and　A　=　0.2.　©　2018　Elsevier　Ltd