Abstract: In order to efficiently obtain high quality information of highway alignment parameters, vehicle position orientation system is adopted to obtain information of dispersed coordinate and attitude, and line type parameters are calculated through post processing. This paper firstly presents a method of initial recognition based on curvature characteristic which is calculated by azimuth filtered by fast median filtering algorithm. Secondly, calculations and accurate recognition of line and circle type parameters are performed. Finally the parameters of approach curve are calculated by adjusted line and circle curve parameters. The method in this paper has been testified at a highway, and the results show that this method is practical.