The　waste　heat　of　internal　combustion　engines　mainly　come　from　exhaust　gas　and　cooling　water.　Usually,　the　exhaust　gas　can　be　recovered　and　utilized　by　organic　Rankine　cycle　(ORC),　and　it　is　hard　for　simple　ORC　to　recovery　heat　from　exhaust　gas　and　cooling　water　simultaneously.　An　ORC　system　coupled　with　a　trilateral　cycle　was　proposed.　Compared　with　a　single　loop　ORC　system,　it　can　improve　the　exergy　recovery　efficiency　of　waste　heat　by　absorbing　both　the　waste　heat　from　the　cooling　water　and　the　exhaust　gas　from　internal　combustion　engines.　The　expander　is　a　key　component　of　the　system.　In　order　to　adapt　to　the　new　system　and　alleviate　the　problem　of　under　expansion,　a　quasi　two　stage　expansion　single　screw　expander　is　used.　It　is　found　that　the　exergy　recovery　efficiency　of　waste　heat　can　be　increased　by　2.81%-5.19%　and　the　temperature　of　organic　fluid　at　the　expander　outlet　can　be　decreased　by　31.23　degrees　C-40.53　degrees　C　compared　to　a　single　loop　system　under　the　exhaust　gas　temperature　of　300　degrees　C　and　the　cooling　water　temperature　of　95　degrees　C.