Lamb波的频散与多模式现象以及复合材料的各向异性限制了复合材料的应用研究。文章以玻璃纤维增强复合材料层合板为研究对象，利用图形法进行Lamb波频散方程求解，由此绘制频散曲线并分析了频散现象，计算了A0，S0的传播速度。搭建了试验系统，基于HHT变换，提取了信号特征并获取了信号的传播速度。结合A0，S0的速度理论值，实现了对Lamb波S0单模式的提取，由此简化了lamb波的使用，使之可广泛应用于复合材料的损伤检测。

The multiple modes and dispersion nature of ultrasonic lamb wave as well as the anisotropies of composite material limit composite material application and research. Taking the glass fiber plate as case study, the paper put forward a graphics method to dispose dispersion equations for plotting the dispersion curve, analyzing the dispersion nature and calculating the velocity of A0 and S0. Based on it, an experim ental test system is set up, the characteristics and velocity of sensor signals are extracted using HHT, according to the calculated value of A0 and S0, the single mode of lamb wave is achieved，which can be used for detecting composite material widely.