A method for producing a solid antifoaming agent comprising the following steps: providing an alkaline solution; adding an oil to the above alkaline solution to produce a saponification reaction; adding a liquid antifoaming agent; and putting aside the mixture containing the above alkaline solution, the oil and the liquid antifoaming agent to form the solid antifoaming agent. The ingredients of the solid antifoaming agent according to the present invention include 5˜40 weight percent vegetable oil, a 20˜40 weight percent sodium hydroxide solution and a 30˜60 weight percent liquid antifoaming agent.