Abstract: The effect of ionic strength and initial protein concentration on the diffusion of bovine serum albumin (BSA) in an anion exchanger, Q Sepharose FF，was studied by batch adsorption experiments.The pore diffusion model was used to analyze the diffusive mass transfer of BSA in matrix pores.The pore diffusivity was determined by fitting the uptake curves of dynamic adsorption for BSA at different ionic strengths and initial protein concentrations,and the pore diffusion coefficient was obtained.The results showed that the pore diffusivity decreased with increasing initial protein concentration.The pore diffusivity increased with increasing NaCl concentration till 0.10 mol•L^-1.However, it became lower at a salt concentration of 0.15 mol•L^-1.This indicated that there existed an ionic strength where the pore diffusion coefficient exhibited its maximum value.