Herein, FeCoCrNiMn high entropy alloy coatings were prepared on 304 stainless steel, using atmospheric plasma spraying technique. The tribo-corrosion behavior of the coating was studied in simulated seawater. Results show that the FeCoCrNiMn high entropy alloy coating was composed of single FCC phase with an average hardness 221.1HV_0.2, in contrast, that of the 304 stainless steel is 159.1HV_0.2. The tribo-corrosion test results showed that in 3.5%NaCl solution, the wear volumes of FeCoCrNiMn high entropy alloy coating under loads 5 N and 10 N differentiated by 17%, which were 1.21 × 10^-2 mm³ and 1.42 × 10^-2 mm³ respectively. The main wear mechanism was believed to be corrosive wear and oxidative wear. The wear volumes of the coating under loads 5 N and 10 N in deionized water differentiated by 11%, which were 1.15 × 10^-2 mm³ and 1.28 × 10^-2 mm³ respectively. The main wear mechanism was also adhesive wear and oxidative wear. The wear volume in NaCl solution higher than in deionized water might suggest that the corrosion effect of NaCl solution promote the wear process. Meanwhile, in NaCl solution, the open circuit potential of the wear samples under lower load could be restored to close to the level before friction motion in a short time during the static soaking stage. However, the open circuit potential of wear samples under higher load increased slowly and was difficult to return to the level before friction motion due to more severe mechanical damage. This phenomenon might indicate that the mechanical damage caused by wear would accelerate the corrosion process.