Gas-liquid two-phase flow exists in processes such as nuclear reactor evaporation, aircraft cooling, and chemical production falling-film evaporation. Dynamic measurement of interfacial waves is of great significance for industrial process monitoring and production optimization. The accurate identification and characteristic parameter measurement of interfacial waves are important prerequisite for scientific research and engineering practice. Based on the ultrasonic phased array measurement system, the measurement method of sector scan is designed, which can be used for liquid film thickness and three-dimensional measurement of interfacial wave morphology with clear gas-liquid interfacial. Through static calibration and circular tube verification, the relationship between pixel points and liquid film thickness is determined. The real-time dynamic experiments are carried out under the gas superficial velocity is 0. 071 9~ 0. 431 6 m/ s and the liquid superficial velocity is 0. 056 7~ 1. 416 1 m/ s. The cross-sectional gas-liquid interfacial information with high accuracy in real-time flow process is obtained, and the three-dimensional distribution of interfacial waves is built, which provides an experimental reference method for the study of interfacial wave characteristics parameters K .