Abstract: The producer gases derived from air and oxygen rich biomass gasification were used as the vehicle fuel for testing the running performance and its emission behavior. The results were as following: under the same road condition and for the same vehicle, the kilometers of travel with air gasification producer gas as fuel were one third of that with oxygen rich gasification producer gas as fuel, and the kilometers of travel with oxygen rich gasification producer gas as fuel were one third of that with CNG as fuel; the producer gas composition had little influence on the carbon monoxide emission in the exhaust gas, but the excess air ratio had crucial impact on the carbon monoxide emission; with air gasification producer gas as fuel, the content of the hydrocarbons in the exhaust gas was lower, and it was higher when being with oxygen rich gasification producer gas as fuel, for both fuel gases, the content of the hydrocarbons had the same tendency of increasing along with the increasing of the RPM of the engine; the producer gas composition had definite influence on the NOx emission in the exhaust gas, meanwhile, the temperature was the dominating factor of the thermal NOx emission. The results showed that the biomass gasification producer gas could be a kind of clean and renewable substitute fuel.