The invention discloses tin plating electrolyte. The tin plating electrolyte comprises the following components 60 to 90g/L of tin methane sulfonate, 10 to 30g/L of tin sulfate, 110 to 140mg/L of p-cresolsulphonic acid, 60 to 120mg/L of sulfosalicylic acid, 30 to 50g/L of phosphinic acid, 45 to 70mg/L of 2,2-PySSPy, 15 to 25mg/L of 8-hydroxyquinoline, 20 to 30mg/L of catechins, 10 to 15g/L of 2,2-dihydroxy diethyl sulfide, 5 to 10mg/L of hexadecylpyridinium bromide, 8 to 12 g/L of dodecyl-phenol polyoxyethylene ether, 5 to 10g/L of ethylene glycol, 4 to 8g/L of benzalacetophenone, 5 to 10g/L of sodium hexametaphosphate, 4 to 8g/L of sodium dodecyl sulfate, and the balance of deionized water. According to the tin plating electrolyte, Sn2<+> can be effectively restrained to convert into Sn4 <+> in an electrolytic process by improving an electrolyte formula, and the stability of plating solution is improved; and meanwhile, the throwing power of the electrolyte is increased, and the luminance, the corrosion resistance and the welding performance of tin coatings are improved.