In this study, octadecyldimethyl(3-triethoxy silylpropyl)ammonium chloride (ODDMAC) incorporated with Polyethylene terephthalate (PET) fabrics with different environmental conditions such as various temperature and time intervals. First, ODDMAC (15 weight %) was dissolved in ethanol. Then PET fabrics immersed in the ODDMAC solution at 25 ℃ for 10 minutes and dried at 80 ℃ for 5 minutes. The dried PET/PDDMAC fabrics carried out for curing process out at 110 ℃ ~ 190 ℃. The treated PET/ODDMAC has examined the surface and side coating properties through SEM analysis and elemental analysis. PET/ODDMAC fabric washed with water up to 50 times and studied the durability of the materials. It was confirmed that the treated PET fabric also exhibited good water repellency. In addition, the antimicrobial activity against the gram-positive bacteria Staphylococcus aureus and gram-negative bacteria Escherichia coli were studied by the disc diffusion method on the treated fabric.