In this paper, a computer-aided method is applied to the detection of horizontal and vertical alignment error during highway construction. The design criterion of highway centerline point corresponding to the detection point of highway midline is put forward. The step-swinging compression method is used to find the corresponding design centerline point. Based on this criterion and the step-swinging approach compression method, highway plane alignment deviation could be divided into transverse deviation and longitudinal deviation along the route. Both the encoding of the types of highway curve and the interval discrimination of the curve of plane alignment are discussed in the step-swinging approach compression method and computer aided calculation of highway plane alignment. Based on these studies, the computer-aided error detection of horizontal and vertical alignment in highway construction is established and used in the project Highway Survey and Design Software Development Integrated in Hunan Province China. Software examples and other examples provided in this paper show that this method is feasible.