Abstract: This experiment is to study effects of different additives, in which the water hyacinth were ensiled by adding additives as following fermented green juice (FGJ), sucrose (SUC), formic acid (FA), foraform (FOR), fermented green juice plus sucrose (MIX) and without additives (control). Each treatment was two repeats. Ensilages were stored in incubators at 30℃, and ensilaged for 40 days, then measured the fermentation quality and chemical composition of silage. All the additives reduce the pH value, ammoniacal nitrogen and neutral detergent fiber of silage（P<0.01，P<0.05）. All the additives except FOR enhanced dry matter rate of silage while reduced moisture content and acid detergent fiber of silage（P<0.01，P<0.05）. And gas loss rate were reduced by all the additives except sucrose（P<0.01）. Besides, all the additives except fermented green juice increased water-soluble carbohydrate（P<0.01）. Results showed that all of the five additives could improve the quality of water hyacinth silages, and the MIX is the best.