在浅海环境中目标散射回波受多途干涉和边界反射干扰，导致目标散射特征易被界面混响与传播效应掩蔽而难以识别。研究聚焦于目标镜面反射回波与多种环绕波相干叠加所形成的稳定共振特征，在浅海环境中构建基于简正波的散射声场模型，计算球体目标在不同深度下的距离-频率谱，分析横向共振条纹的形成机理，推导共振谱谷值所对应的频率间隔与目标半径的定量关系，得到尺寸预报公式。设计水槽缩比实验，采集多深度实心弹性球回波，获得距离-频率谱，提取共振谱谷频率及其间隔。结果表明，共振谷频率位置对目标深度变化具有良好的稳定性，利用所提公式实现对目标尺度的准确估计，说明共振频率具备浅海复杂环境下目标探测与识别的潜力。

In shallow water environments, target scattered echoes are affected by multipath interference and boundary reflections, which can easily cause the target scattering features to be masked by interface reverberation and propagation effects, making them difficult to identify. This study focuses on the stable resonance features formed by the coherent superposition of the specular reflection echo and various circumferential waves. A scattered acoustic field model based on normal modes is established for shallow water, and the range–frequency spectra of a spherical target at different depths are calculated. The formation mechanism of transverse resonance stripes is analyzed, and the quantitative relationship between the frequency spacing of the resonance spectral valleys and the target radius is derived, yielding a size estimation formula. A scaled water tank experiment is designed in which the echoes of a solid elastic sphere at multiple depths are collected to obtain the range–frequency spectra, from which the resonance spectral valley frequencies and their spacing are extracted. The results show that the frequency positions of the resonance spectral valleys exhibit good stability against target depth variations. The proposed formula achieves accurate estimation of the target's geometric scale, demonstrating that resonance frequencies have the potential for target detection and identification in complex shallow water environments.