Abstract: Business processes built from web services need a more adaptable composition solution. In this paper, an approach based on agents is proposed to control the executions of business processes via agent behavior rules, which can be generated automatically and modified dynamically to enable the adaptations of business process. In the approach, the adaptations of the business process are specified in independent adaptation units and agents can load and interpret user-defined adaptation units at runtime. Thus, the executions of business processes can be adapted dynamically. This paper also describes a running support of lightweight agents on a reflective middleware, on which agents can be generated automatically to compose web service to support adaptable business processes according to the specifications of business processes and the adaptation units.