In agent architecture, an active goal is a functionally self-contained entity with independent control flow. The related syntax of active goal and the operational semantics of active goal execution are presented. Furthermore, the BDI agent architecture driven by active goals is formally specified. Different from some former BDI agent architectures, goals are explicitly represented in the agent architecture as active entities. Parallel goals are supported in the architecture level by a very natural fashion, which is considered to be an important aspect of the rational behavior of agent. What’s more, the explicit definition of goals provides convenience to the reconsideration of commitments for agents situated in dynamic environments.