Polyamic acid (PAA) made from 3,3, 4,4-biphenyltetracarboxylic dianhydride and 4,4-diaminodiphenyl ether was synthesized and used as the backbone of nanoporous polyimide. Thermally labile polyethylene glycol (PEG) at 10, 20 or 30 wt% was introduced to the end group of PAA. Self-assembled PAA-b-PEG micelle-like nanoparticles could be formed as a result of amphiphilic characteristics of hydrophobic PAA and hydrophilic PEG. Thermal imidization and degradation of spin-coated amphiphilic PAA-b-PEG film were performed sequentially through one-step heat treatment to obtain polyimide film with nanopores. Pore sizes decreased with increasing amount of PEG block and their dielectric constants decreased from 2.71 +/- 0.13 to 2.38 +/- 0.11.