In this article, electrospinning technique has been demonstrated for the synthesis of ultra-low dielectric constant polyimide fiber membranes. Poly(amic acid) fiber membranes have been prepared as precursor. After the treatment of thermal imidization, ultra-low dielectric constant polyimide fibers membranes can be obtained. The morphologies and structures of precursors and products are characterized by scanning electron microscopy (SEM), Fourier transmission infrared (FTIR) spectra, and a radio frequency (RF) impedance/capacitance material analyzer. The DK of the as-prepared polyimide membrane ranges from 1.53 to 1.56, which could be applied in the electronic packaging industry.