Abstract: Nitrogen is essential to the plant. It makes important effects which promote the growth of the plant, increase the yield. So the nitrogen fertilizer became one of the limiting factors which control the yield. Howerver,if too much nitrogen fertilizer is applied into the soil, it will result some problems. Nitrate residue in the soil produces many problems to the environment. So many scientists made some good processes on the urease inhibitor and nitrification inhibitor. They used the inhibitors to reduce the pollution which the nitrate residue existed in the soil.