Abstract: A method for the determination of lead isotope ratio (208Pb/204Pb, 207Pb/204Pb, 206Pb/204Pb) in sediment samples by thermal ionization mass spectrometry (TIMS) has been developed. A new type of anion exchange resin AGMP1M is used in separation and purification of Pb in sediment samples with low concentration of HCl as eluting reagent to avoid the use of HBr, which is difficult for purification effectively reduce the regent blank. Pb isotope Standard Reference Material NIST NBS981 has been repeatedly measured and the results are in good agreement with certified values with precision of less than 0.5％(2s). The method has been applied to the determination of Pb isotope composition in 5 sediment samples with satisfactory results.