Abstract: PEK ultrafiltration membrance with molecular weight cultting off 6.8×10⁴ was preared.The effect of the polymer concentration the temperature of the coagulating media and other conditions on the performance of the membrance was discussed,under the condition of operating pressure 0.30 MPa,the water flux is more than 100mL/(cm²·h),the physical and chemical stability of the UF membrance was studied too.