Corrosion potential measurement,electrochemical impedance spectroscopy(EIS) and scanning electronic microscopy(SEM) were employed to study the inhibition of hexamethylenetetramine(HA) on corrosion of AZ31 magnesium alloy in simulated coolant.HA exhibits good inhibition after the inducement period through strong adsorption on AZ31 magnesium alloy surface.The addition of HA improves the corrosion resistance of the alloy and affects the corrosion potential little.HA is a mixed-type inhibitor that inhibits both anodic and cathodic reactions of AZ31 magnesium alloy in simulated coolant.