The invention provides a method for testing the content of aluminum oxide in aluminum metaphosphate, which is simple to operate, rapid and accurate. The method comprises the following steps: (1) measuring a test sample, adding a sodium hydroxide solution into the test sample until the sample is completely dissolved, and adding hydrochloric acid until the solution is acidic; (2) adding an ethylene diamine tetraacetic acid standard solution, uniformly stirring, adding several drops of phenolphthalein, neutralizing by utilizing ammonia water until the solution is red, then adjusting the solution to be colorless by utilizing the hydrochloric acid, and adding an additional drop of the hydrochloric acid; adding ammonium acetate, heating and boiling, adding several drops of a xylenol orange solution, and titrating by utilizing a zinc sulfate standard solution until the solution is red; (3) adding a sodium fluoride solution, heating and boiling, and titrating the solution to be red by utilizing the zinc sulfate standard solution; (4) calculating a result. The sodium hydroxide solution is used for rapidly dissolving the test sample, so that the method has the advantages of easiness in operation, simplicity, rapidness, high accuracy and the like.