The work aims to analyze the effects of sulfate on the tin plating of the sulfate-p-toluenesulfonic acid system from corrosion resistance and electrochemical behavior of plating and stability of plating solution and investigate the maximum con-centration range of sulfate in the methanesulfonic acid plating solution without affecting the performance of the plating solution. The effect of sulfate on the corrosion resistance of tinplate was investigated by salt spray experiments and electrochemical tests. The electrochemical behavior of sulfate in tin plating with methanesulfonic acid was studied by electrochemical tests and the visible light spectrophotometer and zeta potentiometer were used to analyze the effect of sulfate on stability of tin plating solution. From the test results, with the increase of the sulfate concentration in the bath, the corrosion resistance of the coating was the best at 5 g/L. When the concentration of sulfate was higher than 10 g/L, the sulfate concentration tended to decrease. During the deposition of tin, the sulfate ions increased the cathodic polarization of tin deposition. When the concentration of sulfate in the bath reached 60 g/L, the cathodic polarization curve did not increase significantly. From the curve of light transmittance over time, when there was no sulfate in the mixed solution of MSA and methanesulfonic acid, the oxidation rate of the solution was slow, and the solution light transmittance decreased from 99% to 86% after 196 h. The oxidation rate of bath could be accelerated when the concentration of sulfate in the solution was 20, 40, 60 and 80 g/L, respectively. After 196 h, the transmittance decreased to 15%, 66%, 63% and 20%. The addition of sulfate also changed the zeta potential of the solution and transformed the colloidal particles from positive charge to negative charge. When the concentration of sulfate in the plating solution exceeds 10 g/L, the corrosion resistance of the tin plating layer decreases. The sulfate radical can increase the cathodic polarization of tin deposition and accelerate the oxidation of tin ions. Moreover, sulfate radicals are adsorbed on tin colloid to reduce the cloud point of the additive.