Abstract: A feature modeling method for generating streamlined structure covered with freeform surface is proposed, and successfully applied to the streamlined structure design of 200?km?h electrical train, Pioneer. The solid model described by streamlined structure feature could be automatically adapted to the remodeling of freeform surfaces of high-speed train. The approach makes it easy to access or change parameters of the streamlined structure; and the streamlined structure solids could be automatically regenerated after the parameters of the streamlined structure are changed. The time spent on human computer interaction is greatly reduced during the design process, as a results the problem on how to shorten the long period of structure design is largely solved.