Surface modifying macromolecules (SMMs) were synthesized and blended into the casting solution of polyethersulfone (PES) membranes. The solution was cast to films on the glass plate. The cast films were placed in a temperature-controlled oven with forced air circulation to remove the solvent, before being immersed into water at 4degreesC for gelation. The following effects on the properties of the PES membranes were found. 1) Mechanical strength of the PES membrane was enhanced by adding SMMs. 2) According to the contact angle measurement, surface hydrophobicity of the PES membrane increased as solvent evaporation period increased. X-ray Photoelectron Spectroscopy (XPS) detected surface migration of SMMs 3) SMM blended PES membranes have potential to be used for the purpose of membrane distillation.