The invention discloses a corroding method of a DD5 single-crystal high-temperature alloy turbine blade. The method includes the following steps of firstly, sand blasting; secondly, primary chemical corroding, wherein a 40% ferric trichloride solution and a 37% hydrochloric acid solution are used for preparing a corroding solution, and chemical erosion is conducted on a cast in the first step for9 minutes; thirdly, primary washing, reactants adhering to the surface of the cast and generated during chemical erosion in the second step are washed away through an ultrasonic washing machine, the ultrasonic frequency is 20 KHz, the water temperature is 50 DEG C, and the washing time is 5 minutes; fourthly, secondary electrochemical corroding; fifthly, secondary washing; sixthly, tertiary electrochemical corroding; seventhly, neutralizing, wherein the cast in the six step is placed in a 5% NaHCO3 room-temperature solution to be soaked for 3 minutes, and acid liquid on the surface of the castis neutralized; eighthly, drying. The corrosion effect is clear, and it can be avoided that due to local excessive corrosion, surface structure and appearance size of the cast are not qualified.