Structural depth of pavement is a key indicator to reflect pavement macroscopic structure. A measurement method using laser-displacement-sensors is presented. Based on this method, an improved least square method is used to remove the trend of pavement, and then the structure depth of pavement can be calculated. A detection system including hardware and software is developed, which can achieve accurate and rapid measurement in applications. Reliability and performance of the developed system were tested in some experiments. The results show that the presented method can measure the structure depth of pavement accurately and rapidly.