Abstract: The 1 000 h reliability experiment was carried out on the common rail diesel engine using BD5 biodiesel. The wears of engine parts were investigated after experiment. By dismantling and examining the engine parts, processing traces or visible light of major friction journal could be observed, and there was a small amount of coke at the valve. The wears of the main moving parts were measured after the reliability experiment. The wears of piston, connecting rod, crank group and valve train were analyzed. The results showed that, the diesel engine could burn biodiesel for long time without problem, after 1 000 h test, the wear of oil ring for cylinder 4 was 0.004 mm, the wear of small rod for cylinder 3 was 0.043?mm, the wear of crankshaft for cylinder 2 was 0.003 mm. The maximum subsidence of valve for cylinder 1 and cylinder 2 was 0.009 mm. During the experiment, the parts of diesel engine were not broken, peeled off, ablation or bonded. Burning biodiesel had no exceptionally influence to the diesel major parts.