In the field of highway infrastructure, the flatness, slope, and curvature during initial construction have undergone rigorous testing to ensure high-quality standards in the early stages. However, with the passage of time, the dual effects of natural environment (such as internal stress changes caused by temperature differences, material aging caused by long-term sun and rain exposure) and traffic load (continuous rolling of vehicles with different loads) gradually lead to problems such as decreased smoothness and weakened strength of the road surface. Due to the difficulty in directly observing the inherent strength of roadbeds and pavements, subtle changes in pavement smoothness often become a key indicator for evaluating their health status. The total length of highways in our country has exceeded 5.441 million km. Traditional manual inspection methods are not only inefficient, but also costly, making it difficult to meet such a huge demand for inspection. In this context, the displacement capacitance leveling instrument stands out with its advantages of automation, high precision, and high efficiency, becoming an ideal choice to solve this problem.