In this paper, the fractionation of Pb isotope during the purification procedure is assessed,and the purification methods for isotope determination by MC-ICPMS are described. Purification procedure indeed leads to the mass fractionation of Pb isotope through AG1-X8 anion exchange resin. Though the fractionation is very small (0.43‰ amu^-1), it is beyond the instrument error apparently (0.23‰ amu^-1). The very low recovery of Pb during the purification procedure would cause Pb isotope value to deviate from the real value. With AG1-X8 as exchange resin,0.2 mL 1 mol/L HBr solution as loading solution, 5 mL 1 mol/L HBr and 0.5 mL 2 mol/L HCl solution as eluent for cleaning up the impurities,and 1.5 mL 6 mol/L HCl solution as eluent for desorption of the Pb adsorbed by the resin, the value determined after the purification of sample by using the separation procedure would be close to the true value within error. Under such a condition,the early fractions of the eluate are systematically enriched in the light isotopes (δ²⁰⁸Pb >0),whereas the late fractions of the eluate are systematically enriched in the heavy isotopes (δ²⁰⁸Pb >0),which indicates that the heavy Pb isotopes partition is absorbed more strongly into the resin than the lighter isotopes,and the distribution coefficient of Pb absorbed into the resin ²⁰⁸D/²⁰⁴D >1. Pb isotope fractionation may happen with the exchange of Pb in different types of complex compound in the desorption process, which implies that Pb isotope fractionation would occur in the reaction including inorganic compound or organic macromolecules. The results achieved by the authors not only enrich the knowledge of Pb isotope fractionationbut also provide more information for the analysis and application of Pb isotopes.