In order to more accurately detect the hidden diseases in the structural layer of the white and black pavement, relying on the white and black pavement of Maozhan Expressway reconstruction and expansion project, the three-dimensional ground penetrating radar technology was used to carry out the disease detection of the existing pavement, and the structural bearing capacity of the white and black pavement was tested combined with the falling weight deflectometer. The results show that the three-dimensional ground penetrating radar equipment can clearly identify the internal condition information of white and black pavement structure, such as broken plate, crack, void and force transmission rod layout, which can reflect the overall situation of the internal layer diseases of the original pavement structure. Under the action of vehicle load for many years, the proportion of reflective crack disease of white and black pavement is high. It is proposed to adopt grouting, crack pouring and other maintenance measures to strengthen the stability and watertight treatment of old cement board and asphalt layer .After overlaying the asphalt layer on the cement pavement, the deflection value of the top of the road decreases as a whole. The deflection difference with or without asphalt layer is mainly related to the thickness, modulus and aging degree of asphalt overlay. In order to better simulate the load effect of actual wheel load on pavement, it is recommended to use 10 t load to test the deflection difference between slabs, and take the deflection difference above 0.05 mm as the treatment threshold to carry out targeted reinforcement treatment.