To investigate the deposition and adsorption behavior of BSA on the PVDF surface and the structure of the BSA adsorption layers over a range of ionic strengths, a quartz crystal microbalance with dissipation monitoring (QCM-D) combined with a self-made PVDF-coated sensor crystal was used in this study. These results were combined with those of fouling experiments and the flux recovery rate (at corresponding ionic strengths) to obtain visual insight into the effect of ionic strength on membrane BSA fouling behavior.Results show that when the ionic strength increased from 0 to 1 mmol/L, the adsorption amount of BSA on PVDF surface was increased, and a denser and more compact BSA layer was formed, accompanied by the enhancement of membrane fouling, which was mainly attributed to the decrease of electrostatic repulsion forces. But on the contrary, when ionic strength increased to 10 and 100 mmol/L, the PVDF-BSA and BSA-BSA interaction forces are weakened due to an increase in the hydration repulsion force, which results a decrease in adsorption amount of BSA on PVDF surface, a more nonrigid and soft BSA layer was formed, and membrane fouling decreased significantly. Moreover, the flux recovery rate was increase significantly at high ionic strength.