Abstract: Two kinds of alfalfa and timothy with high and low moisture content were made silages to study the effects of alfalfa fermented with green juice (AFGJ),timothy fermented green juice (TFGJ),lactic acid bacteria(LAB),cellulose (CEL) and lactic acid bacteria(LAB)+cellulose (MIX) on fermentation quality of alfalfa and timothy silages. Each treatment had two repeats. Silages were fermented for 50 days. The fermentation quality of silages were observed. The fermentation quality of alfalfa and timothy silages were significantly affected by additives(P<0.05), all the additives improved the fermentation quality of alfalfa and timothy silages with high and low moisture content, but there were no significant role in high moisture content alfalfa silages with AFGJ and TFGJ. The fermentation quality of alfalfa and timothy silages were significantly affected by the moisture content(P<0.05),the fermentation quality of both alfalfa and timothy silages with low moisture content were better than that with high moisture content silages. There were significant interaction between the additives and moisture content(P<0.05). The fermentation quality of alfalfa silage with high and low moisture content with MIX were the best; the fermentation quality of timothy silage with high moisture content with FGJ and TFGJ were similar,but the quality were better than other additives. The fermentation quality of timothy silage with low moisture content with AFGJ,TFGJ,LAB and MIX were similar ,but the quality were better than CEL. The results showed that the treatment by reducing the moisture content and choicing the additives could improve silage quality.