Abstract: A new kind of lowheattransfer D.I． diesel engine which can burn vegetable oil is introduced.　The effects of lowheattransfer combustion system on the oil ignition　and combustion were discussed.　The engine performances,economic index and exhaust were analyzed. According to the lowheattramsfer idea， an heatisolation technique was used in the design of the piston top． This new engine can not only use vegetable oil as fuel， but also decline the NO_x，HC exhaust. The consumption rate of vegetable fuel is 15 ％ higher than that of the diesel fuel． For getting the same dynamic performance the fule of vegetable oil should be increased．