Abstract： Objective To study the compatible stability of cefathiamidine for injection with four infusions with different pH values.Methods According to the pH range of four infusions in China pharmacopoeia(CP),pH of 0.9％ sodium chloride injections,5％ dextrose injections,10％ dextrose injections and 5％ dextrose +0.9％ sodium chloride injections were adjusted.According to the clinical common dose,the compatibility solutions between cefathiamidine and infusions and infusions unadjusted were confected.pH value,color and external appearance changes (color and clarity) of the 12 compatibility solutions were determined at 0,0.5,1,2,3,4,5 and 6 h.The high performance liquid chromatography(HPLC) assay was performed for determining the content of the four compatibility solutions at the same time.BDS-C18 chromatographic column (250 mm ×4.6 mm,5 μm) was used;the mobile phase was phosphate buffer liquid and acetonitrile (80∶20) ; the detective wavelength was 254 nm; the temperature was 30 ℃ and the incoming sample amounted to 1 μl.Results This method achieved baseline separation.The linear range was within 1-12 mg/ml.Relative standard deviation(RSD) of intra-day was less than 2％.Peak area was relative steady and decreasing degree was less than 4％ within 6 hours.Conclusion After the compatibility of cefathiamidine and 0.9％ sodium chloride injection,cefathiamidine and 5％ dextrose injection,cefathiamidine and 10％ dextrose injection and cefathiamidine and 5％ dextrose +0.9％ sodium chloride injection with different pH values during 6 hours at room temperature can keep an relative stability and can be used for clinie.