Four kinds of petroleum coke with different sulfur content were used as raw materials to prepare sulfur and nitrogen co-doped carbon materials by potassium hydroxide activation. The microstructure, graphitization degree, pore size structure, and surface element state of the prepared materials were characterized and analyzed. Four carbon-based materials prepared by petroleum cokes with different sulfur content were applied as HI (1 mol/L) +H2SO4 (0.5 mol/L) solution electrolytic anode materials. The electrochemical properties of their electrocatalytic I- oxidation to I2/I-3 were investigated. The electrochemical properties of the materials, such as cyclic voltammetry, linear scanning, and AC impedance, were studied. Combined with the characterization results, the effect of nitrogen and sulfur doping on catalytic oxiding of I- was discussed. It was concluded that pyridine nitrogen could be used as the catalytic active center. Meanwhile, S in graphitic plane network structure could induce polarization of adjacent C and N atoms, and a new electrocatalytically active center is formed. More mesoporous pores contribute to the dissolution and diffusion of I-3 ions from electrode surface into solution. The carbon material prepared with sulfur content of 4.6% has the highest pyridine-N content, and the larger average pore size is conducive to the diffusion of I-3 ions, so the corresponding electrochemical activity is optimum.