The objective of this study is to investigate membrane fouling caused by ultrafiltration (UF) when reusing tertiary effluent in an industrial park. A bench scale membrane system was performed. Experimental results showed that the removal of iron, manganese, and turbidity wale 62%, 30%, and 77%, respectively. From the infrared ray analysis of membrane fouling, one can see that the organic functional groups were aromatic hugs and a few linear chair, compounds of chromophore and auxochrome found in dyestuff. Therefore, tertiary effluent may induce both colloidal and organic fouling into the UF system.