In order to solve the problem of reliable evaluation in distributed system under Internet environment, we study on trust model which is an effect method of trust and robust in distributed system. Based on historic interactive information between entities, we define and value the behavior trust, and provide a reference data for the establishment of the trust model. In the paper, we introduce the basic concept and the research status of trust models, and deeply analyze the key problems and solutions on trust model. Through the study of some classic trust model, we discuss the existing issues in the present research.