Abstract: The effect of adding ethanol on fermentation quality of elephant grass (Pennisetum purpureum) silage was studied. Ethanol was added at 0, 1.5%, 2.5%, 3.5%, 4.5% of fresh weight, and the silos were opened after 1, 3, 5, 7, 14, or 30 days of ensiling and the fermentation quality was analyzed. Ethanol addition inhibited protein break down and significantly (P<0.05) reduced the ammonia nitrogen/total nitrogen as compared with the controls. The pH of silage with ethanol decreased slowly during initial 3 days of ensiling and then dropped faster. The lactic acid content tended to increase during ensiling and reached its highest value on about day 7. The lactic acid content of silage with ethanol addition was higher than that of the control on the 30th day of ensiling. At an early stage of fermentation the WSC (water soluble carbohydrate) content declined very quickly. The WSC utilization efficiency of silage with ethanol was higher than that of the control. Addition of ethanol significantly (P<0.05) lowered the acetic acid content compared with the control on days 1 and 14 of ensiling, but there was no marked (P>0.05) difference between the silages with ethanol added. The above experiments suggested that addition of ethanol inhibited the use of protein and WSC by aerobic bacteria and thereby reduced silage losses during the early stages of ensiling. This provided more fermentation substrate for lactic acid bacteria, which produced more lactic acid, and improved the fermentation quality of elephant grass.