OBJECTIVE:To establish a method for the content determination of polymer in Cefotaxime sodium and tazobactam sodium(6∶1)for injection. METHODS:High performance size exclusion chromatography(HPSEC)was performed on the column of TSK-GEL G2000SWXL with mobile phase of 0.01 mol/L phosphate buffer (pH 7.0) at a flow rate of 1.0 ml/min,detection wavelength was 254 nm,injection volume was 10 μl and the column temperature was 25 ℃. RESULTS:Cefotaxime and the poly-mers were well-separated;the linear range of cefotaxime was 2.3-226.4 ng(r=0.999 9);RSDs of precision and reproducibility tests were no more than 0.79%;results of durability test showed the changes of column temperature,flow rate,wavelength,pH and mobile phase salt concentration had little effects on the separation among different polymer peaks and between polymer peaks and main peaks. CONCLUSIONS:The method is simple,specific and sensitive,and can be used for the content determination of poly-mer in Cefotaxime sodium and tazobactam sodium(6∶1)for injuction.