This paper aimed to prepare a new anti-corrosion composite coating to enhance the corrosion resistance of 316L stainless steel in medium and high temperature sulfuric acid solution. The chemical oxidation method was used to in-situ-polymerize polyaniline (PANI) on the surface of graphite(G) particles to prepare PANI/G composite material, and then epoxy resin (EP) was added as a film forming agent to prepare PANI/G/EP composite coating. The electrochemical performance, adhesion and conductivity of PANI/G/EP composite coating was compared with that of PANI/EP composite coating and PANI/GO/EP composite coating prepared by adding graphene oxide (GO). Then, the influence of the ratio of graphite to polyaniline on the electrochemical performance of PANI/G/EP composite coating was explored. The chemical bond and micro structure of PANI/EP composite coating and PANI/G/EP composite coating were characterized by fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and X-ray energy spectroscopy (EDS). The scratch immersion test was used to compare the protective effect of PANI/EP composite coating and PANI/G/EP composite coating on stainless steel when there are small defects. Finally, the protection mechanism of PANI/G/EP composite coating on stainless steel was discussed based on the experimental results. Comparative experiments showed that the PANI/G composite material and the PANI/G/EP composite coating both had the highest electrical conductivity (1.66 S/cm and 8.93×10?3 S/cm respectively), and the PANI/G/EP composite coating sample had the best adhesion (about 5.23 MPa), and it showed the best electrochemical performance. In 1 mol/L sulfuric acid solution at 50 ℃ and 60 ℃, the self-corrosion potential of PANI/G/EP composite coating was significantly increased by 580 mV and 470 mV respectively, both reached the stable passivation zone of stainless steel, and the current density of the anode polarization curve dropped significantly. The electrochemical AC impedance test showed that the impedance modulus of the sample increases significantly after the coating is applied. The investigation of the graphite ratio in PANI/G composite material showed that the coating has the best anti-corrosion performance when G∶PANI= 2∶100. The scratch immersion test showed that after being immersed in 1 mol/L sulfuric acid solution at 50 ℃ for one week, the exposed substrate at the defects of PANI/G/EP composite coating samples hardly corroded. Graphite (G) can effectively improve the conductivity of the composite coating and strengthen the anode protection effect. In the medium temperature sulfuric acid solution, the PANI/G/EP composite coating can provide physical shielding and more significant anodic protection at the same time, and shows a significant corrosion protection effect for stainless steel.