Highly　transparent,　flexible,　low　percolation　threshold　and　conductive　nanocomposite　membranes　were　prepared　by　mixing　poly(aniline-co-sulfonic　aniline)　(PANSA)　nanoparticle　suspension　with　cellulose　diacetate　solution　under　ultrasonic　wave　for　2　hr,　and　then　by　casting　the　solution　onto　glass　plate.　PANSA　nanoparticles　were　synthesized　by　oxidative　copolymerization　of　aniline　and　2-methoxyaniline-5-sulfonic　acid　in　hydrochloric　acid　aqueous　solution　with　ammonium　peroxydisulfate　as　oxidant　without　emulsifier　or　stabilizer.　With　increase　of　nanoparticle　load,　conductivity　of　the　nanocomposite　membrane　increased,　which　could　meet　demand　of　antistatic　material.　Conductivity　of　the　nanocomposite　membrane　was　steady　below　150°C.