The　organic　Rankine　cycle　(ORC)　is　regarded　as　one　of　the　most　promising　methods　to　increase　the　efficiency　of　diesel　engines.　Owing　to　the　variability　of　exhaust　energy　with　engine　speed　and　load,　the　ORC　should　be　designed　for　various　operating　conditions　of　engines　for　optimal　waste　heat　recovery　(WHR).　In　this　study,　an　integrated　simulation　model　of　the　diesel　engine-ORC　combined　system　(the　combined　system)　is　built　by　GT-Suite.　Based　on　the　model,　the　MAPs　of　optimum　parameters　are　obtained　by　an　artificial　neural　network　(ANN)　and　a　genetic　algorithm　(GA).　Subsequently,　operation　modes　of　the　combined　system　under　various　conditions　are　proposed.　Finally,　a　control　strategy　of　switching　operation　modes　and　adjusting　parameters　that　adapts　to　various　conditions　of　diesel　engines　is　developed　by　GT-Suite　and　MATLAB/Simulink.　Simulation　results　show　that　the　optimum　pump　speed　is　steady　approximately　1000　r/min　under　the　low　load　region　of　the　engine　and　increases　with　the　engine　load　when　the　engine　speed　is　higher　than　1800　r/min.　By　contrast,　the　optimum　expander　speed　is　1500　r/min　in　all　selected　engine　operating　conditions.　Further　investigations　indicate　that　the　performance　of　the　combined　system　presents　improvements,　with　a　3.57%　increase　in　thermal　efficiency　and　a　10.09　g/(kW.h)　reduction　in　brake　specific　fuel　consumption　(BSFC)　when　compared　against　the　original　diesel　engine.　These　preliminary　results　prove　that　the　integrated　simulation　model　can　be　used　for　further　research.　Meanwhile,　with　regard　to　the　proposed　control　strategy,　more　thorough　experimental　research　needs　to　be　conducted.