Abstract: Because of the higher viscosity and the worse volatility,the diesel engine can hardly perform normally using neat vegetable oil. The durability test of L28 diesel engine fueled with vegetable oil was completed after the fuel injection pressure was increased and a fuel pre-heating device was installed. The feasibility was discussed and the diesel engine problems caused by fueling with vegetable oil for a long time were pointed out. The specific fuel consumption, smoke and exhaust temperature before and after the durability test were compared and analyzed. The results show that after 100 hours full load running, there are heavy carbon deposit in the nozzle, valve, piston head and cylinder top; the lubricating oil is polluted by the leaked vegetable oil; there are little change in fuel consumption, smoke and exhaust temperature.