A method in the study of validation for quimoline phosphomolybdate solution in determination of fertilizer wasdeveloped.The sample weighing of potassium dihydrogen phosphate and the influence of nitric acid solution werestudied，and the method conditions were determined.The content of phosphorus pentoxide in potassium dihydrogen phosphate wasanalyzed by validation method and compared with the theoreticalvalue(52.21%).Considering the measurementerror，thefailure of quimoline phosphomolybdate solution was judged when the analysis result was less than52.0%.The method hasgood precision and high accuracy，and is suitable for the validation verification of quimoline phosphomolybdate solution in determination of fertilizer.