In this paper, the synthesis of Co3+ by electrooxidation and the synthesis of P-methyl sulfone benzoic acid by oxidation of P-methyl sulfone toluene were systematically studied.Studies have shown that lead dioxide anode, cathode lead electrode plates, ceramic membrane as a cation exchange membrane and electrolyte concentration to C(Co2+)=0.5 mol/L, C(sulfuric acid)=4.0 mol/L, C(ammonium sulfate)=0.15 mol/L, electrode spacing d=2cm, the current density J=350 A/m2, electrolytic temperature t=10 ℃, the electrolyte Co2+ conversion rate could reach 80% and the electrolytic oxidation current efficiency was 67.5%.In the matrix oxidation process, the concentration of electrolyte C(Co3+)=0.4mol/L, C(sulfuric acid)=4.0 mol/L,C(ammonium sulfate)=0.15 mol/L, the mole ratio of Co3+ and thiamphenicol toluene 6:1, reaction temperature 30 ℃ and reaction time 30min, the yield of benzoic acid thiamphenicol could reach 97.8% and purity was 99% after refining.