Effects of different nitrogen application rates on productiveness of Puccinellia chinampoensis Ohwi were studied in the paper.The results showed that applying nitrogen fertilizer has significant effect on the increase of seed and herbage yield.The optimal effect was achieved when 138 kg of nitrogen was applied per hectare.Seed and herbage yield of this treatment in third year after sowing were 613.33 kg/hm² and 7 100.40 kg/hm²,with an increase of 177.1% and 102.1% compared to the control.Increase of seed and herbage yield per 1 kg nitrogen was 2.8 kg and 26.0 kg.Seed and herbage yield of this treatment in fourth year after sowing were 524.40 kg/hm² and 6 807.60 kg/hm²,with an increase of 209.7% and 232.1% compared to the control.Increase of seed and herbage yield per 1 kg nitrogen was 2.6 kg and 34.5 kg.The application of nitrogen increased the plant height and density and raised crude protein content of herbage.