Choose a saucepan large enough to fit a mixing bowl inside, fill it with a few inches of water, and set it on the stove over medium heat. When the water is simmering, place the mixing bowl inside.  Make sure that the water level isn't so high that you risk getting water in the mixing bowl. The water should not be boiling; if it begins to get too hot, reduce the heat. Put the egg whites, sugar, and corn syrup in the bowl. Stir them until they're completely combined, and continue stirring as the sugar dissolves and the mixture heats up. Use a candy thermometer to check the temperature of the icing; when it reaches 160 degrees, it's ready to be beaten.  Keep a close watch on the temperature of the icing, as it could easily overcook. If the icing seems quite slow to warm, increase the burner temperature. It should reach 160 degrees within 2 or so minutes. Use a whisk or an electric mixer to beat the icing until it turns fluffy and glossy. Add the vanilla and continue beating for a total of five minutes. Remove the icing from heat and use it to frost your cake.

TL;DR in Chinese:
在装着热水的炖锅上放一个搅拌钵。 煮糖霜。 搅拌糖霜。