Changes of rice yield character of different nitrogen use efficiency varieties under different nitrogen application level were analyzed in the study.The results showed that comparing with low nitrogen level,high-nitrogen utilizable varieties under medium-high nitrogen condition,high-nitrogen and high-effect varieties under high nitrogen,the plant height increased greatly,ears per unit area increased greatly,at the same time,the grains per ear increased obviously,especially when nitrogen was high.So the two kinds of varieties had higher number of flowers per unit area than other kinds of varieties,while low-nitrogen utilizable varieties appeared oppositely.In low medium high-nitrogen utilizable varieties,most of whose grains per ear increased a little when medium nitrogen to high nitrogen.Though the number of flowers per unit area was high,and increased range of flowers was large when it was from low nitrogen to medium nitrogen.whereas increased range of flowers became less when it was from medium to high nitrogen.The analysis of correlation showed that the count of ears influenced yield greatly when at low medium nitrogen,while the function of grains per ear was great to yield when at high nitrogen level.So in the breeding of super rice,materials of big ears,especially those materials which increasing range of grains per ear was big at high nitrogen should be chosen.