Polypropylene microporous membranes were treated with plasma in a mixture of N2 and H2 (1:2 in volume). Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FT1R), X-ray photoelectron spectroscopy (XPS) and ultra-violet (UV) spectra demonstrated the success of grafting amino groups. The density of the polar amino groups on the membrane surface is about 0.59 μmol/cm2. The as-treated membranes were successively applied to the in situ synthesis of oligonucleotides and an average coupling yield was more than 98%. The surface feature of the treated membrane is suggested to be responsible for its advantage over a glass slide. Polypropylene microporous membranes were treated with plasma in a mixture of N2 and H2 (1: 2 in volume). Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FT1R), X-ray photoelectron spectroscopy (XPS) and ultra- The demonstrated of success of grafting amino groups. The density of the polar amino groups on the membrane surface is about 0.59 μmol / cm 2. The as-treated membranes were applied applied to the in situ synthesis of oligonucleotides and an average coupling yield was more than 98%. The surface feature of the treated membrane is suggested to be responsible for its advantage over a glass slide.