Nano-structured polyaniline have been synthesized by interfacial polymerization method at room temperature. An aqueous solution of aniline in chloroform and another solution of ammonium peroxydisulfate in doping acid were prepared at different times terminated with methanol at room temperature. SEM, UV-vis were used to characterize the polyaniline with regard to their morphology and structure. The diameter and length of polyaniline can be controlled by the reaction time. Nano-structured polyaniline were found to have superior sensitivity for volatile organic compounds(VOCs). As the reaction time to increase from 30minute to 2hours the sensitivity were decreased to VOCs vapors. The sensitivity of Nano-structured polyaniline sensor appeared to VOCs better than the sensitivity of chemical synthesis sensors. The sensitivity of Nano-structured polyaniline sensor improved benzene vapors.