Curves are an important component of road traffic scenes. In road information reconstruction through visual information, it is difficult for the traditional world coordinate system built by the surveillance camera to represent the real road spatial information and vehicle position information in a curve scene. To solve this problem, this study proposes a mileage coordinate system based on road alignment. In this system, the horizontal direction represents distance information along the road section, and the vertical direction represents mileage information along the road alignment. For the construction of the mileage coordinate system, camera calibration and proposed result optimization are firstly carried out through the calibration algorithm based on a single vanishing point and the road prior information to obtain the real spatial positions of the lane lines or road edges. Then, with the real spatial information of lane lines or road edges in the world coordinate system, polynomial fitting is performed to obtain the fitted road alignment curve. Finally, the road identification points or vehicle track points are projected onto the fitted curve to acquire the distance information based on the road section direction and the distance information in the road direction. This scheme is tested in a simulated experimental curve scene and an actual highway curve scene. The experimental results show that the average position errors of the proposed mileage coordinate system are both less than 5% in the simulated curve scene and the actual scene. Compared with the traditional straight-line world coordinate system, this system, with favorable adaptability and high precision, can meet actual requirements.