Abstract: The bonding status between asphalt pavement layers has an important influence on the mechanical properties and service life of the pavement. To study the inter-layer bonding status of asphalt pavement under vehicle load, an approach based on 3D ground penetrating radar (GPR) technology was used to estimate the bonding status between asphalt pavement layers. The approach is able to analyze the inter-layer bonding status of the asphalt pavement. It is found that the peak amplitude of the reflected radar wave is able to describe the contact state between asphalt pavement layers; the amplitude reflected by the interface obeys the log-normal distribution; the peak amplitude less than 1.0 mm (good interlay bonding) accounts for 70% of the total area; and areas with amplitude values greater than 2.0 mm (poor interlayer bonding) account for less than 3%. Results show that the bonding status of the driving lane and the passing lane are better than that of the emergency lane. Furthermore, the investigation is able to provide necessary theoretical and technical support for pavement interlayer bonding status evaluation.