Abstract: An icing detection method based on ultrasonic guided wave optimization mode is presented. Taking the ice-aluminum plate double-layer structure as the research object, the semi-analytical finite element (SAFE) model is established, and the guided wave dispersion curve and wave structure are obtained. Several modal frequency points are selected from the dispersion curve, and the sensitivity of different modal ultrasonic guided waves to icing is analyzed by simulation, which is verified by the ice-aluminum plate structure icing detection experiment. The results show that the ultrasonic guided wave with sensitive mode can detect the existence of ice, and the minimum ice area with a diameter of 20 mm can be detected.