In order to improve the efficiency of plate structure defect detection, an ultrasonic local resonance detection method based on wideband excitation is developed in this paper. The maximum betweenclass variance method is used to analyze and process the ultrasonic field under broadband excitation, and the ultrasonic local resonance frequency of the defect is obtained. The acoustic field spatial distribution under ultrasonic local resonance frequency is used in the detection and imaging of the plate structure damage. Aiming at the isotropic plate structure with specific material and thickness, the relationship model of defect size and ultrasonic local resonance frequency is established by means of the uniform design test. The experiment results show that the developed ultrasonic local resonance detection method can effectively achieve the damage detection of isotropic and anisotropic plate structure. With the regression analysis model, the inversion of the geometric parameters of the defects can be achieved, and the inversion precision is high (the maximum radius inversion error is 2 mm, and the maximum thickness inversion error is 06 mm). This study provides a feasible technical scheme for the defect detection and quantitative analysis of plate structure.