The purpose of this study was to study the corrosion inhibition effect of sodium benzoate, sodium tartrate, sodium citrate and glycine in chemical mechanical polishing (CMP) of magnesium alloys. Using malic acid, alumina abrasive, deionized water and different corrosion inhibitors to configure different polishing fluid. The chemical mechanical polishing experiments were carried out under the same conditions, such as the type of polishing pad, the rotation speed of polishing disc, the flow rate of polishing fluid and the type of pH regulator. The polishing magnesium alloy sheet was characterized by 3D white light interferometry, and the corrosion inhibition mechanism was analyzed by electrochemical corrosion test and X-ray photoelectron spectroscopy (XPS). The results show that sodium tartrate and sodium benzoate have the best inhibition effect under acidic conditions. Both sodium tartrate and sodium benzoate inhibit the further corrosion of magnesium alloy by promoting the oxidation of dissolved oxygen in the polishing solution to the surface of magnesium alloy and forming passivation film. The corrosion inhibition of magnesium alloy passivation film formed in solution containing sodium benzoate is higher than that in solution containing sodium tartrate. Both sodium benzoate and sodium tartrate are involved in the formation of passivation film, but XPS analysis shows that the magnesium content in the surface film of magnesium alloy soaked with sodium benzoate solution is less than that of passivation film soaked with sodium tartrate solution. The electrochemical corrosion experiments show that the positive movement of corrosion potential of magnesium alloy in the solution containing sodium benzoate is greater than that of magnesium alloy in the solution containing sodium tartrate, which proves that the inhibition effect of sodium benzoate is better than that of sodium tartrate at the same concentration. Under acidic conditions, the inhibition effect of sodium benzoate was stronger than that of sodium tartrate. In the CMP process of polishing pressure 22 kPa, polishing speed 60 r/min, abrasive 20 nm α-Al2O3, adding 1wt.% sodium benzoate, the polishing surface quality is the best, Ra=(3.594±0.194) nm. Both sodium benzoate and sodium tartrate are anodic corrosion inhibitors, which can form passivation film on the surface of magnesium alloy. The increase of corrosion potential means that magnesium ions need to overcome a larger barrier to transfer from magnesium alloy surface to solution.