The work aims to develop a novel composite coating to protect 316L stainless steel in hot sulfuric acid solution for long term. The primary doped polyaniline (PANI) was prepared by chemical oxidation method, dodecylbenzenesulfonic acid (DBSA) doped polyaniline was obtained by dedoping-redoping process, and epoxy resin (EP) was used as the film former to prepare PANI/EP composite coating. The functional groups, structures and morphologies of the materials were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The electrochemical tests and scratch immersion tests were used to evaluate the anti-corrosion performance of PANI/EP composite coating, and the protection mechanism of the composite coating was discussed. In 1 mol/L sulfuric acid solution of 50 ℃ and 60 ℃, the corrosion potential of the PANI/EP coated sample increased significantly by 560 mV and 450 mV at 50 ℃ and 60 ℃ respectively compared to stainless steel, reaching the passivation potential range of stainless steel. The current density of anodic polarization curve decreased by two orders of magnitude, and the EIS test showed that the impedance modulus of the PANI/EP coated sample increased significantly. The scratch immersion test showed that after immersed in 1 mol/L sulfuric acid solution of 50 ℃ for one week, the PANI/EP composite coating did not fall off, and there was almost no corrosion at the scratches. The main reason was that the stable passive film formation was promoted by coating. Therefore, the PANI/EP composite coating can provideboth physical shielding and anodic protection to the stainless steel in medium temperature sulfuric acid solution and have good corrosion protection effect.