A novel and efficient method for the electroless silver plating polyimide fabric was developed with electromagnetic shielding properties. Firstly, polyaniline (PANi) was in situ polymerized with ammonium persulfate used as oxidizing agent. Secondly, Ag+ was in situ reduced to Ag0 by PANi, and the electroless silver plating was initiated by Ag0 used as active center. Fourier transform infrared, scanning electron microscopy, X-ray diffraction, contact angle analysis and energy dispersive spectroscopy were used to characterize the composite fabric. It could be observed that silver layer-coated polyimide fabric was compact and uniform with surface resistance about 0.02 Ω/sq. The thermal stability was evaluated by thermogravimetric analysis. The as-prepared fabric had excellent anti-corrosion, tensile strength and fastness. The shielding effectiveness of this fabric could reach 54–90 dB, which implied it was a good candidate as electromagnetic shielding materials in many fields.