In the Internet-age, the geographical boundaries that have previously impinged upon inter-organization collaborations have become decreasingly important. However, ensuring secure and authorized access to remote services and information resource in a dynamic collaborative environment is a challenging task. According to some recent literatures, trust between users in different security domains or organizations is an effective method to this problem. However, only trust is not enough because of the complexity and burden of authorization. So we integrate role into our trust model to simplify the management of access control. Moreover, in order to make the dynamic collaboration between different domains more secure, we present the constraint to authorization and operations of the users in foreign domains.