In the present research, double-layer chitosan (CS)/polyvinyl alcohol (PVA) polyacrylonitrile (PAN) and single-layer PAN nanofibrous membranes were prepared by electrospinning method. The blend weight ratio of CS/PVA and concentration of PAN solutions were varied to obtain the optimal electrospun mats in terms of fiber diameter, porosity, and pore size. The 50/50 CS/PVA was determined as the optimal top layer with respect to the obtained results. Moreover, the electrospun nanofibrous membranes were characterized by wastewater treatment. The maximum rejection values of chemical oxygen demand (COD), total dissolved solids (TDS), and turbidity using CS/PVA-PAN nanofibrous composite membranes were 61.14, 34.6, and 99.8%, respectively. Such findings imply that the electrospun nanofibrous composite membranes can be used as appropriate membranes for pretreatment process.