RT_B, the language describing behavior-driven trust management, is given. Variables are introduced into roles to maintain the cumulate behavior status of the users. Behavior-Driven credentials modify users’ assigned local roles in a trust domain according to the behaviors enforced by the users. Combined credentials improve the efficiency of trust determination. Trust policy update credentials allow trust domains to update trust policies automatically when the system statuses are changed. Implementation framework of behavior-driven trust management is described. Several optimization mechanisms of realization are discussed.