Surface modification of membrane is one of the alternatives to reduce the membrane fouling and increase the number and variety of membranes prepared for new and improved applications. polyethersulfone hollow fiber membranes are widely used in ultrafiltration seperation due to their excellent chemical resistance, good thermal and mechanical properties, but because of their natural hydrophobicity, protein molecules are absorbed on the surface and membrane pores, causing severe fouling and flux reduction. The goal of this project is to modify the surface of the PES hollow fiber membrane using GO nanoparticles. For this purpose, three modifications were made on the membrane surface. In the first step, PES membrane was modified with AA by UV irradiation. In the second stage, the surface of the membrane was carboxylated, modified by diethylene tramine by chemical method. In the third stage, graphene oxide was bonded to the surface of the membrane containing amine bonds and corrected by chemical method. The results of FESEM and Surface Infrared Spectroscopy (ATR-FT-IR) studies of modified membranes in comparison with unmodified membrane show that graphene oxide is covered on the surface of the PES membrane. The results of measuring the contact angle of the water showed that the contact angle of the modified membrane with graphene oxide (GO-DETA-AA-PES) was reduced to 46% relative to the pure membrane and the PES membrane surface hydrophilicity improved significantly after bonding with nanoparticles. Ultrafiltration experiments showed that the performance of the modified PES membrane with graphene oxide improved significantly and the pure water flux in the modified membrane increased by 69% relative to the pure membrane. Also, by measuring the flux ratio recovery of modified membrane flux, 44% showed improvement in anti-ejection properties.