In an undisturbed column experiment,the nitrogen leaching losses in the powder soil and blue clayey paddy soil was studied by applied urea with new nitrification inhibitor 3,4-dimethyl pyrazole phosphate(DMPP).The results showed that,within the 60 days of the experiment,in the powder soil and blue clayey paddy soil,the accumulative leaching losses of soil nitrate in treatment with DMPP were 66.8% and 69.4% lower,while ammonium-N were 9.7% and 6.7% higher than normal urea treatment,respectively,and the accumulative leaching losses of soil(ammonium nitrate)-N were 59.1% and 63.0% lower.After experiment,inorganic nitrogen content in the 0~15 cm layer soil were 28.2% and 34.1% larger,and the nitrogen vertical transfer was greatly declined.The fact that the application of DMPP could obviously decrease the nitrogen leaching losses from soil could contribute to the nitrification inhibitor effects of DMPP on the retard of ammonium nitrification for about 60 days.It is suggested that the DMPP could be used as an effective nitrification inhibitor to control the nitrate leaching losses and minimize the underground water pollution risk.