Abstract:AlCoCrFeNi high entropy alloy was prepared by vacuum arc melting furnace and annealed at 600 ℃, 800 ℃ and 1000 ℃ for 10h. The microstructure of the alloys before and after annealing and their ?corrosion resistance in 3.5% NaCl solution, 0.5 mol/L NaOH solution and 0.5 mol/L H2SO4 solution were studied Using XRD, SEM, EDS and electrochemical corrosion test. Organizational analysis shows that there is no complex intermetallic compound in as-cast and annealing states; the alloys in as-cast and 600 ℃ and 800 ℃ annealing states are composed of simple BCC crystal structure and have the branch crystal morphology; in 1000 ℃ annealing state the alloy consists of BCC + FCC and Short rod-like FCC precipitate phase and BCC substrates arrange alternately; in as-cast and three temperature annealing states, Co, Fe and Ni distributions are uniform and Cr, Al are certain segregation; Al segregation in as-cast is the most serious and Cr segregation in 800 ℃ annealing state is the most serious. Electrochemical corrosion test results show that AlCoCrFeNi alloys in as-cast and three temperature annealing states have excellent corrosion resistance in 3.5% NaCl solution and 0.5 mol/L NaOH solution; in 3.5% NaCl solution, the 1000 ℃ annealing alloy has the best corrosion resistance; in 0.5 mol/L NaOH solution, the four states of the alloy have similar corrosion resistance; in 0.5 mol/L H2SO4 solution, the four states of the alloy have occurred the phenomenon of passivation and 1000 ℃ annealing state has the minimum dimension passive current density and the highest break blunt potential, and its corrosion resistance is best.