This standard specifies a method for the determination of total nitrogen content in phosphorus nitrate and phosphorus potassium nitrate fertilizers. Titrimetric method after distillation, nitrate and nitrite are first reduced to ammonium ions, followed by distillation of ammonia under alkaline conditions, ammonia is absorbed with excess sulfuric acid, and in the presence of indicator, back titration is carried out with sodiumhydrate standard solution. This method is suitable for nitrate phosphate and phosphorus potassium nitrate fertilizers produced by various processes, and the determination range of total nitrogen content is wide. The standard specifies the requirements for the use of relevant reagents and solutions, and emphasizes safety precautions when handling corrosion reagents.