The invention relates to the field of ultrasonic equipment application, and aims at providing a three-step method for applying ultrasonic equipment based on amplitude control to a chemical engineering device. The method is mainly implemented in the three steps that firstly, experiment-grade small-scale test equipment is calibrated, and an amplitude curve in small-scale test production is drawn; then, pilot-scale test ultrasonic equipment is manufactured and verified; finally, the ultrasonic equipment for industrial production is manufactured and applied. By means of the method, ultrasonic intensity can be accurately metered, and comparability of an experimental result and reproducibility of experimental data can be achieved; by controlling the amplitude of the ultrasonic equipment, design of the pilot-scale test equipment can be guided, it is ensured that the pilot-scale test equipment can reproduce the experimental result of the small-scale test equipment, and a solid foundation is provided for final design of a production line; the purpose of guiding the ultrasonic equipment to be perfectly applied to the chemical industry production device with a standard process and strict data is achieved; it is guaranteed that a wrong way is avoided, and the experimental effect of a lab is accurately reproduced on the large-scale production line.