Frequent　fluctuations　of　CNG　engine　operating　conditions　make　the　waste　heat　source　have　uncertain,　nonlinear,　and　strong　coupling　characteristics.　These　characteristics　are　not　conducive　to　the　efficient　recovery　of　the　DORC　system.　The　systematic　evaluation　of　the　CNG　engine　waste　heat　source　and　the　comprehensive　performance　of　the　DORC　system　is　conducive　to　the　efficient　use　of　waste　heat.　Based　on　the　theory　of　internal　combustion　(IC)　engine　thermal　balance,　this　paper　analyzes　the　dynamic　characteristics　of　compressed　natural　gas　(CNG)　engine　waste　heat　energy　under　full　operating　conditions.　Then,　based　on　the　operating　characteristics　of　the　dual　loop　organic　Rankine　cycle　(DORC)　system,　thermodynamic　models,　heat　transfer　models,　and　economic　models　are　constructed.　The　dynamic　response　characteristics　analysis　and　energy,　exergy,　and　economic　(3E)　evaluation　of　the　DORC　system　under　full　operating　conditions　are　carried　out.　The　results　show　that　the　maximum　values　of　net　power　output,　heat　exchange　area,　and　the　minimum　values　of　EPC　(electricity　production　cost)　and　PBT　(payback　time)　are　all　obtained　under　rated　condition,　which　are　174.03　kW,　25.86　kW,　37.54　kW,　24.76　m(2),　0.15　$/kW　&　BULL;h　and　3.46　years.　Therefore,　the　rated　condition　is　a　relatively　ideal　design　operating　point　for　the　DORC　system.　The　research　in　this　paper　not　only　provides　a　reliable　reference　for　the　comprehensive　analysis　and　evaluation　of　the　performance　of　the　DORC　system,　but　also　provides　useful　guidance　for　the　selection　of　appropriate　DORC　system　design　operating　points.