Polyaniline(PANI) doped with hydrochloride (HCl), dodecylbenzene sulfonic acid (DBSA) or amino sulfonic acid (NH2SO3H) were prepared by in-situ polymerization. Effects of acid content, reaction time, oxidant ammonium persulfate(APS) dosage and reaction temperature on conductivity of PANI were studied. The presser resistance and thermal stability of them were compared. Results show that the conductivity of HCl-PANI was the largest 198 s.m-1 under the C(HCl) 0.5 mol.L-1 ，reaction time 6.0 h, n(APS):n(aniline)=1.0 among them; The conductivity of NH2SO3H-PANI was 26 s.m-1 under the C(NH2SO3H) 1.0 mol.L-1 ，reaction time 6.0 h, n(APS):n(aniline)=2.0; The conductivity of DBSA-PANI was 98 s.m-1 under the C(DBSA) 1.0 mol.L-1 ，reaction time 8.0 h, n(APS):n(aniline)=2.0. The presser resistance of HCl-PANI was the least 10Ω, and that of NH2SO3H-PANI was the largest 120Ω. The order of their thermal stability is DBSA-PANI > NH2SO3H-PANI > HCl-PANI before 350℃, and the order is HCl-PANI > NH2SO3H-PANI > DBSA -PANI after 350℃.