Modified membrane separators with lower cost using non-woven Polypropylene (PP) were widely used in the field of the secondary lithium batteries. Sulfonation is one of the most commonly modified methods for the surface modification of polymers. In order to make it effective in industry production, plasma surface treatment is applied to one, and it is an effective surface activation technology without changing its original properties. The characteristic properties of modified PP membrane separators have been studied by Alkali Absorption property Test, Tensile Strength Test, Fourier-Transform Infrared Measurements (FTIR), Scanning Electron Microscopy (SEM) and X-Ray Photoelectron Spectroscopy (XPS). Sulfonic acid groups in the polymer membranes were evidenced by the FTIR and the XPS spectroscopy. The results showed that the plasma sulfonation treatment reaction was very effective to improve the surface hydrophilicity of the non-woven membranes. The suitable sulfonation process could keep the lower cost in industry production.