A sensitive method for the determination of the total content in nitrophosphate.The method was based on a seriers of reaction and quantitative relationship between nitrate and urea.A definite amount of urea was added in the sample to take part in the reaction.Conditions of reaction were experimentally optimized.Nitrogen was finally determined by titration with standardized NaOH solution and calculated from the losses of amide nitrogen.The method is proved that it is feasible by experiments.