Abstract: In order to study the water quality and plant characteristics of rice-ditch-pond system under the condition of application of fertilizers with different ratio of dairy manure to chemical fertilizers, paddy field and artificial ditch pond system under different ratios of dairy manure and chemical fertilizer were studied. Water samples of the system were collected regularly and analyzed(pH, COD, TN, TP, NO₃^--N, NH₄⁺-N concentration). At the same time, the biomass and nitrogen and phosphorus content of plants in ditch, pond and rice were analyzed. The results show that the TP concentration of 70% chemical fertilizer +30% dairy manure(70% F+30% M) in paddy field was significantly lower than that of other three fertilization treatments. Although there was a significant difference between different treatments, COD concentration was at a low level(class Ⅲ of surface water standard). There was no significant difference in concentrations of TN, NO₃^--N, NH₄⁺-N. The yield and the contents of nitrogen and phosphorus of 70% F+30% M were higher. Ditch-pond system for paddy field water purification effect was up to class Ⅲ of surface water standard as a whole. The purification rate of COD was 28.91%-51.77%, and of TP was 79.59%-91.57%, of TN was 4.19%-46.28%, of NO₃^--N was 6.82%-31.26%, and of NH₄⁺-N was 7.77%-41.42%. The the highest plant biomass of ditch-pond system was Trapa incisa + Trifolium repens, which was 13.55 t·hm^-2. The plant with the highest N content was Myriophyllum verticillatum, which was 16.26 g·kg^-1, and the plant with the highest P content was Zizania latifolia + Festuca elata, which was 2.91 g·kg^-1. In terms of comprehensive biomass and nitrogen and phosphorus content, the plant with the highest yield of N and P were Myriophyllum verticillatum and Trapa incisa + Trifolium repens, respectively, with yield of 100.26 kg·hm^-2 and 39.43 kg·hm^-2. In conclusion, dairy manure is the best substitute for fertilizer at a rate of 30%, The paddy-ditch-pond system can effectively purify high TP and COD concentrations brought by dairy manure in water, and the best purification effect are Myriophyllum verticillatum and Trapa incisa + Trifolium repens.