Abstract: In order to improve the corrosion resistance of mild steel in marine environment,Ni-Sn-Mn alloy coatings were prepared on the surface of Q235 steel by pulse electrodeposition.The effect of bath temperature on coating element content,surface morphology,deposition rate,cathode current efficiency and corrosion resistance was investigated by glow discharge spectroscopy （GDS）,scanning electron microscopy （SEM）,Tafel curve and electrochemical impedance spectroscopy （EIS）.The results showed that with the increasing bath temperature,the content of Ni and Sn decreased at first and then increased,while the content of Mn raised firstly and then dropped; coating deposition rate and cathode current efficiency increased; corrosion resistance of coatings strengthened firstly and then weakened. The coating prepared at the bath temperature of 30 ℃ was uniform and compact,and had the biggest corrosion potential（-0.374 V）,the smallest corrosion current density（4.266×10^-8 A·cm^-2）,the biggest charge transfer resistance（7 459 Ω·cm²） and exhibited the best corrosion resistance in 3.5% NaCl solution.