In order to provide theoretical basis and technical support for the utilization of biogas slurry, a field experiment was conducted to investigate the effects of different ratios (0、25%、50% and 75% ) of biogas slurry nitrogen, which substituted chemical nitrogen fertilizer, on the yield and quality of aquatic vegetables (Oenanthe javanica). The results indicated that the yields of Oenanthe javanica amended with 25%, 50% and 75% ratio of biogas slurry were 6.05%, 66.67% and 44.44%, respectively, which were all higher than that amended with chemical fertilizer treatment. The highest yield of Oenanthe javanica appeared in the treatment amended with 50% ratios of slurry, which was 82 541 kg/hm2. There were no significant differences in chlorophyll, carotenoid, vitamin C, cellulose and protein contents in the stem and leaf of Oenanthe javanica between different ratios biogas slurry treatments and chemical fertilizer treatment. The soluble sugar contents in stem and leaf of Oenanthe javanica of other four treatments were lower than that of chemical fertilizer treatment. Compared with chemical fertilizer treatment, nitrate contents in treatments with biogas slurry application ratio of 25%, 50% and 75% were decreased by 6.3%, 31.9% and 18.6%, respectively. In conclusion, the application of biogas slurry for substitution of chemical nitrogen fertilizer on Oenanthe javanica could promote the growth of Oenanthe javanica and improve its quality, also could reduce the nitrate contents of Oenanthe javanica. In this paper, the best slurry application ratio was 50% or so.