Abstract: Using a thermostat water bath, the methods to display the original austenite grain boundaries of EH690 steel for offshore platforms after different temperature heat-treatment process were systematically studied. The results show that:the method that the specimens were etched by the etchant of 150 mL supersaturated solution of picric acid+3-5 g shampoo+1-5 drops of hydrochloric acid in water bath cauldron at 46℃ could clearly display the original austenite grain boundaries of EH690 steel for offshore platforms.