On-road　emission　measurements　of　two　typical　China　III　heavy-duty　diesel　trucks　with　and　without　diesel　oxidation　catalytic　converter　(DOC)　and　catalyzed　diesel　particulate　filter　(CDPF),　have　been　conducted　by　using　a　portable　emission　measurement　system　(PEMS).　The　results　indicated　that　real-world　emissions　of　CO,　THC,　solid　particle　number　(SPN)　and　black　carbon　(BC)　from　the　two　retrofittedvehicleswere　(1.31±0.37)　g/(kWh),　(0.20±0.03)　g/(kWh),　(7.13×1010±5.27×1010)particle/(kWh)　and　(0.69±0.06)　mg/(kWh),　respectively.　Compared　with　the　original　emissions　(i.e.,　DOC+CDPF　removed),　these　emissions　were　reduced　by　52.48%,　55.69%,　99.91%　and　99.22%,　respectively.　From　low-speed,　medium-speed　to　high-speed　driving　conditions,　the　reduction　ratio　of　CO　and　THC　showed　an　upward　trend,　butthere　was　no　significant　difference　in　the　emission　reduction　of　SPN　and　BC　under　various　operating　conditions.　Retrofitting　with　DOC+CDPF　had　no　significant　reduction　effect　on　NOx　emissions,　which　were　9.53　to　9.83g/(kWh),　higher　than　the　emission　limit.　However,　the　proportions　of　NO2　in　NOx　were　increased,　and　the　elevations　got　enhanced　from　low-speed,　medium-speed　to　high-speed　driving　conditions.　©　2020,　Editorial　Board　of　China　Environmental　Science.　All　right　reserved.