Abstract: Polyaniline was doped with ptoluene sulfonic acid(TSA) using a method of redoping.The effect of doping time and concentration of ptoluene sulfonic acid aqueous solution on the conductivity and structure of polyaniline was studied.A fourprobe technique and FTIR were employed to explore the doping mechanism.The thermal stability of doped polyaniline was studied by TG.When the doping time was 12 h and the TSA concentration was 0.5 mol/L,the best conductivity was observed.