Objective: To establish a HPLC method to determine the content of the starting material of Avibactam sodium (2S,5R)-Ethyl 5-[(benzyloxy)amino] piperidine-2-carboxylate. Methods: Hypersil ODS2 chromatographic column(4.6mm×250mm, 5μm)was used.Mobile phase A was 0.01 mol/L ammonium dihydrogen phosphate solution, and mobile phase B was acetonitrile. The running time from mobile phase A to mobile phase B (50:50) was 11 minutes with the flow rate of 1.0 mL/min, the wavelength of 210 nm, the column temperature of 40 ℃ and the calibration amount of 10 μL. Results: Avibactam Sodium starting material (2S,5R)-Ethyl 5-[(benzyloxy)amino] piperidine-2-carboxylate was well separated. Conclusion: HPLC is sensitive, rapid, accurate and reliable to determine the content of Avibactam starting material (2S,5R)-Ethyl 5-[(benzyloxy)amino] piperidine-2-carboxylate.