Trust-based delegation authorization mechanism is regarded as an effective method for computational resource access in open dynamic environment. One important problem is how to apply more grain subjective trust control on delegation and authorization procedure. On this paper, the problem is probed and a trusted role based logic model on the semantic of attribution authorization mechanism is proposed. The concepts of trusted role and trust constraint are proposed. The computational method for entity decrease trust value in delegation is given in logic model. The trust control policy for delegation and the trust control rule for authorization based on role trust evaluation and entity trust evaluation respectively are put forward. The policies and rules are expressed in logic syntax and the semantic of delegation authorization logic program is given out. Finally, the soundness and completeness of logic system are proved theoretically.