A new bilayer electrospun nanofiber membranes consisting of a hydrophobic silver nanoparticle-based polyimide nanocomposite (Ag-PI) supporting layer and hydrophilic poly(vinyl alcohol) (PVA) barrier layer for oily wastewater treatment application has been presented. First of all, the Ag-PI electrospun nanofibrous supporting layer was fabricated through electrospinning and thermal treatment from polyamic acid containing silver carbamate. After that, the PVA electrospun nanofibrous barrier layer was constructed by electrospinning onto the supporting layer and chemical crosslinked. The silver nanoparticles were uniformly formed through thermal-reduction of silver carbamate in nanofiber, homogeneously. The constructed bilayer electrospun nanofiber membranes were characterized by the permeate flux, rejection rate, and antimicrobial activity of Escherichia coli and Staphylococcus aureus . It was found that they showed strong antimicrobial activity as well as a high flux and high rejection rate at low operating pressure.