This study is devoted to engine application of bio-diesel manufactured by transerification reaction with alkali process from waste cooking oil. The performance & pollutant emission of vehicle engine application are little different in the idle condition for the engine test of the garbage collecting trunk with PD (practical diesel), B20 (20% biodiesel mixture with diesel) and B100 (100% biodiesel). In the full loading condition, the pollutant degree is decreased obviously with the addition of biodiesel especially for full alternative B100 for PD. The CO emission is down 51%, the SOx emission is down 73%, the NOx is down 13%, and, the carbon participate emission is down 69% in this test. But, the decreasing motion horsepower (down 10%) and the increasing fuel consumption (up 11.3%) are the evidences that the above effect is focused on the healthy to the environment only.