The invention relates to a method for detecting dynamic modulus of each layer of an asphalt pavement and an adhesion device. The method comprises the following step of detecting the dynamic moduli of an upper surface layer, a middle surface layer and a lower surface layer of an original pavement. According to the method disclosed by the invention, an SPT (Simple Performance Tester) or a loading device which is capable of applying offset sine wave type or haversine wave form load, is in a frequency range of 0.1 to 25 Hz, can achieve 2800KPa of maximum stress application level and is capable of achieving 5N of loading resolution ratio is adopted. Offset sine wave or haversine wave type axial pressure stress is applied to each core sample layer, restorable axial strain of a testing piece can be measured, and uniaxial compression dynamic modulus within an online viscoelasticity range of each layer of the asphalt pavement in service can be calculated. Harsh requirements of an existing dynamic modulus detecting device on sizes of core samples are met; according to the method, the measurable thickness range of the core samples is 3 cm to 15 cm, and the method can be used for calculating material parameters of each layer of an existing asphalt pavement, evaluating the current situation of each layer of the asphalt pavement in service and forecasting the residual life of an old pavement.