Abstract: The display effects of grain boundary of high strength steel A-100 were analyzed by different chemical etchant. The display time of grain boundary in etching solution at different temperatures was measured by thermostat water bath, and the morphology of grain boundary was observed by metallographic microscope. The results show that the optimum etching solution for grain of high strength steel A-100 is supersaturated picric acid+eagle brand detergent solution (crystalline shape) or supersaturated picric acid+white cat brand detergent solution (crystalline shape). When the temperature of etching solution is 40℃ or 45℃, the clear display of grain boundaries takes the shortest time.