Abstract: Through our investigation on the amount of N fertilization in Jiangshan single season later-rice production, we have found that average rate of N application per hectare was 240kg in 2004, over the average rate of China. So rice cost of production was high and N-fertilizer use efficiency was low. Furthermore, environmental pollution by nitrogen leaching or runoff from rice fields has become a serious concern, rate from investigation with it has been reduced from 10%~30%, and were used to study yields of rice, quality of rice, N-fertilizer use efficiency and N loss rates in 2005.The result showed that compared with custom of farmers used N-fertilization, rice yields increased about 27% with the N-fertilization reduced from 15%~25%. N-fertilizer use efficiency changed in the range of 20.7%~46.9% with the amount of N-fertilization applied, the more the N used, the lower N-fertilizer use efficiency. N loss rates and the amount of N-fertilization applied kept same step, N loss rates per hectare changed in the range of 32.1kg~80.1kg, the more the N used, the more N loss rates, and nitrite content of rice too. It shows that many farmers use excessive N rates in single season later-rice production. We should reduce it.