The architectural design service, a knowledge intensive industry, expands rapidly in China. Upgrading the service level becomes an important issue for managers and the assessment of architectural design services is a multiple criteria decision making (MCDM) problem. Many traditional MCDM methods are based on the additive concept along with the independence assumption, but criteria may be dependent in some situations. The decision making trial and evaluation laboratory (DEMATEL) can be used as a wise method to handle the inner dependences within a set of criteria. In this paper, DEMATEL approach is proposed to assess architectural design services more effectively. In addition, a case study is presented to make this approach more understandable for managers.