Web services for CAD (WSC) aims at interoperation with a commercial CAD system based on Web services. This paper introduces one improvement of WSC which enables remote users to retrieve assembly model data using Web services. Much time is required in retrieving assembly model data. To resolve this problem, this paper proposes to use the parallel Web services. As assembly model comprises a set of part models, it is easy to subdivide the problem into smaller sub-problems. In addition, Web services inherently support distributed computing. This characteristic makes the parallel processing of Web services possible. The data model, interface and implementation are shown. Results of experiments on the retrieval performance of assembly model data are also shown.