Abstract: Transient surface wave was firstly used to evaluate the conditions of old highway which the layer was hard in the top while soft in the lower,the sensors was improved to adapt to the layer,the frequency spread data of base and high order modal was comprehensively used to forward and inverse the old highway surface wave velocity(SWV) along depth.The statistic relation between SWV and compactness,standard penetration testing number was established through the contrast of maintenance materials and drilling surveying.The experiment results show that the information of base and high order modal was extracted meanwhile to analyze the frequency spread data in the highway structure layer.The base order modal characters reflect the parameter of low velocity layer while the high order modal characters reflect the parameter of high velocity layer.It has a good relationship between weighted layered SWV and compactness,standard penetration number.The research results were used to evaluate the old Hu-Ning highway surface condition.