In order to improve the rationality of the alignment design at the route design stage, the spatial curvature was used as the evaluation standard of highway alignment continuity, by using the VS as the development tool and the C# as the development language, the secondary development of Civil 3D was carried out. The evaluation model based on spatial curvature was established, and a highway alignment evaluation program for the continuity of alignment was developed, which can be used as an extension tool in civil 3D. The program was used to evaluate the alignment continuity of Luotuolazi—Qingyoutun highway in Heilongjiang province. The results show that the proposed highway alignment continuity evaluation program can quickly calculate the spatial curvature and evaluate the alignment safety, which can provide reference for the alignment optimization of highway projects.