The interaction modality constrained to desktop PC between user and WFMS is one of the main factors obstructing business processes to be widely applied in pervasive computing environment. In addition, the increasingly complicated and flexible group activities have been a salient feature of current business processes.Traditional workflow management systems have difficulties in supporting such features. By extending and improving modeling method and executing mechanism of workflow management system, a group-supported system is designed and implemented, which has the ability of interacting with users in multiple modalities. This paper introduces the new modeling method for multifold group activities as well as the mechanism supporting interaction with multiple modalities. Then some outcomes and findings in the applications of the system are discussed.