Abstract：This paper studies exhaust fumes of environment friendly dual fuel automobiles. Samples were collected from taxies fueled by natural gas, such as Shanghai Volkswag?觕n, Citr?觕n, Beijing Hyundai and from other vehicles powered by 93# gasoline in Lanzhou city. Organic matters of the two groups were analyzed, respectively, with GC/MS. The results show that there are 9 olefine, 3 alkane and 6 benzene in the exhaust fumes of Natural Gas Vehicles (NGV); and 9 olefine, 3 alkane, 22 benzene and 4 Polycyclic Aromatic Hydrocarbon(PAH) in the exhaust fumes of gasoline vehicles. Obviously, the exhaust fumes from Natural Gas Vehicles(NGV) contain few carcinogenic benzene substances and PAHs, as compared with those in waste gas from petrol-powered cars.