Conductive polyaniline (PANI) was synthesized by the oxidation of aniline with complex oxidant composed of ammonium persulfate ((NH4)2S2O8) and ascorbic acid (C6H8O6) in a reaction media containing sulfuric acid (H2SO4). The effects of concentration of H2SO4, (NH4)2S2O8 and (NH4)2S2O8/C6H8O6 mol ratio on the polymerization of aniline were studied. The optimal polymerization condition was aniline 1mol/L, H2SO4 1mol/L, and compound oxidant (mole ratio of (NH4)2S2O8 to C6H8O6 as to 10:1) 1mol/L at room temperature without the protection of N2. The conductivity and yield of PANI reach 13.3S/cm and 96.7%, respectively. The structural changes of PANI were measured by FTIR, Raman and XRD. The results indicated that PANI was some crystal and its groups took place red shift.