A method of high performance liquid chromatography with hollow fiber-based liquid phase microextraction(HF-LPME/HPLC) was developed for the analysis of four trace cephalosporin antibiotics,i.e.cefazolin(CZO),cefuroxime(CXM),ceftazidime(CAZ) and cefoxitin(FOX) in water.The optimized conditions were as follows:1-octyl-3-methylimidazolium hexafluorophosphate(［Omin］PF6) added with 10% trioctylphosphine oxide(TOPO) was selected as extraction solvent,in which TOPO was used for assisted extraction.The pH of sample solution was adjusted to 2.5.The extraction was conducted for 20 min at 30 ℃,with a stirring rate of 600 r/min.Four cephalosporin antibiotics were separated within 7 min on an Agilent Poroshell 120 EC-C18 column(100 mm×4.6 mm,2.7 μm) using 0.05 mol/L sodium acetate buffer(pH 4.0)-acetonitrile(9∶1,volume ratio) as mobile phase.Results showed that there were good linear relationships for four cephalosporin with the enrichment factors of 45-78 and the limits of detection(LOD) of 0.2-0.7 ng/mL.Recoveries for the four analytes ranged from 83.2% to 102%,with relative standard deviations(RSD) of 2.0%-9.8%.With the advantages of simple operation,high efficiency,low cost,low solvent consumption,environmental protection and high sensitivity,the proposed method was suitable for the determination of four trace cephalosporin residues in water.