The invention relates to a measurement method of N-methylpyrrolidine content of cefepime dihydrochloride material and relative agent, for evaluating the quality of cefepime dihydrochloride material and relative agent. The invention discloses a liquid chromatograph which comprises using carboxylic cationic column as analysis column, uses a conductive detector to check, preparing flow phase, preparing sample solution and reference substance solution, using test method to respectively inject the sample solution and reference substance solution into a liquid chromatograph, recording high pressureliquid chromatographs, and calculating the N-methylpyrrolidine content of the sample. The inventive chromatograph system has easy balance, short sample test time, better repeatability in preserved time, stable baseline, durable column, high quality of chromatograph peak of N-methylpyrrolidine, better repeatability, accurate, simple and reliable process.