Nanoporous Polyimide has a lower dielectric constant than pristine polyimide but remained good physical properties. Nanoporous polyimide was prepared from thermal decomposition of polyimide-g-poly(ethylene glycol) copolymer, synthesized via Williamson ether synthesis reaction from OH-contained polyimide and Br-terminated poly(ethylene glycol). The incorporated poly(ethylene glycol) in polyimide was investigated by Nuclear Magnetic Resonance (NMR), Thermogravimetric Analysis (TGA) and Gel Permeation Chromatography (GPC). Because of the differencesin thermal stability between polyimide and poly(ethylene glycol), Pores can be generated while polymer film was being cured at 250 ˚C. Moreover, the effects of two variations were investigated. One was the effect of changing ratio DHBP:6FDA which directly influenced on the incorporated poly(ethylene glycol) content in polyimide structure. Anotherwas the effect from changing molecular weight of poly(ethylene glycol). Pore size and pore distribution was investigated by Scanning Electron Microscope (SEM). Mechanical properties were measured by Universal Testing Machine. Dielectric constant was measured by LCR Meter. The lowest tensile strength is 70 MPa and the lowest dielectric constant is 3.8.