The polyethylene glycol ( PEG) removal experiments with different molecular weights were carried out by molecular weight cut off ( MWCO) 8 000 ceramic membrane to investigate the effects on removal of different molecular weights PEG and the fouling mechanism. Pore model was modeled to characterize the effective pore diameter and thickness of the membrane, and the combined fouling model was borrowed to explain the internal factors of ultrafiltration fouling mechanism. Results showed that the pore model was simulated and well characterized for the equivalent pore size of the membrane. The fitting analysis of the membrane structure parameters was obtained through the ultrafiltration process of different molecular weights PEG. The cake?complete blocking model fitted accurately the experimental data for a TMP of 0?3 MPa and a crossflow velocity of 0?5 m/s.