Scanning electron microscope and goniometer were used to investigate morphology and wetting property of polypropylene membrane surfaces modified by plasma treatment using different reagents. Surface morphology was significantly affected by the types of reagents. X-ray photoelectron spectroscopy and attenuated total refection-Fourier transform infrared spectroscopy were used to characterize the chemical structure of polypropylene membrane surfaces modified by Freon-116 gas plasma treatment. Many fluorine atoms were observed on the polypropylene surface, and its concentration increased to saturation with increasing plasma treatment time. The wetting behavior of plasma treated polypropylene membrane was well explained in relation with morphology and chemical structure.