Objective To study the effects of the composite corrosion inhibitor composed by HEDP, SDBS and sodium silicate on the corrosion inhibition efficiency of Q235 steel in peroxyacetic acid solution. Methods The static weight loss method and potentiodynamic polarization curve method were used to study the synergistic effect of sodium silicate and HEDP, SDBS on corrosion inhibition of Q235 steel in the system containing 2000 mg/ L peroxyacetic acid at room temperature. Then the best blending formula was determined and the inhibition mechanism was analyzed. Results HEDP,SDBS and sodium silicate all exhibited certain corrosion-inhibition effect for Q235 steel in 2000 mg/ L peroxyacetic acid. The successive order of inhibition efficiency was sodium silicate and HEDP > sodium silicate and SDBS > sodium silicate. When the mass concentration of sodium silicate was 200 mg/ L and the mass concentration of HEDP was 100 mg/ L, the corrosion inhibition efficiency for Q235 steel could reach 90. 42% . When the mass concentration of sodium silicate was 200 mg/ L and the mass concentration of SDBS was 200 mg/ L, the corrosion inhibition efficiency for Q235 steel could reach 57. 76% . The inhibition efficiency of sodium silicate was up to 40. 53% . Conclusion Sodium silicate had both cathodic and anodic inhibition actions, and exhibited good corrosion-inhibition effect when compounded with HEDP. The inhibition efficiency of sodium silicate and HEDP was better than that of sodium silicate and SDBS. The optimal concentrations of compounded corrosion inhibitors were 200 mg / L of sodium silicate and 100 mg / L of HEDP.