The poly(ethylene-co-vinyl alcohol) (EVOH) ultrafiltration membrane is prepared via pre-evaporation combined thermally induced phase separation (TIPS), using a novel co-solvent that is a mixture of sulfolane and 1,3-propanediol. The porous surface is mainly caused by the low cooling rate of pre-evaporation stage. Based on the shorter pre-evaporation time, the evaporation of 1,3-propanediol provides a foundation for asymmetric structure. Subsequently, the quenching effect of water bath forms a dense layer below the porous surface. The compact degree of dense layer increases first and then decreases with the increase of pre-evaporation time (t) or pre-evaporation temperature (T) or the mass fraction of 1,3-propanediol in co-solvent (beta). Therefore, the rejection of bovine serum albumin (BSA) increases first and then decreases as t or T or beta increases. Meanwhile, the connectivity of membrane structure can also be adjusted by changing beta. Finally, the EVOH ultrafiltration membrane prepared from tau = 20 s, T= 25 degrees C and beta= 15% achieves relatively high BSA rejection of 98% and relatively large pure water flux of 302 Lm(-2) h(-1) bar(-1).