Abstract: HCl-doped emeraldine form of polyaniline（PANI-HCl） was synthesized by chemical oxidative polymerization of aniline,and the electric conductivity and dielectric coefficient of the PANI-HCl with different thermal treatment temperature was studied.In addition,the effect of thermal treatment under air atmosphere on the doping degree and microstructure of the PANI-HCl was also investigated by using FT-IR,TGA,DSC and XRD.The results show that PANI-HCl has excellent electrical conductivity and dielectric coefficient when treatment temperature is below 100℃ and the conductivity magnitude is 100 and the loss tangent（tgδ_ε） is between 0.35~0.49.The conductivity magnitude decreases rapidly to 10^-7 and tgδ_ε is below 0.1 when the treatment temperature is up to 160℃.The reasons of variation of the electric conductivity and the dielectric coefficient contribute to the loss of dopant and the change of microstructure of the PANI-HCl.