With the in-depth researches of large scale distributed systems, such as Grid computing, Ubiquitous computing, P2P computing, Ad hoc networks, etc, system is a dynamic and cooperative model made up of multi-software serving. Under these dynamic and uncertainty environments, trust mechanism based on CA (certificate authority) in a regular PKI (pubic key infrastructure) can’t adapt to these requirements. Dynamic trust mechanism is a new and hot topic of security research for these new distributed applications. In this paper, firstly, the concepts, problems, and research approaches of dynamic trust relationship are summarized and presented. Secondly, several typical dynamic trust model systems including their mathematical methods are described in detail. And then, this paper presents the results of comparative evaluation of these models under a selection of scenarios. Finally, the current problems and the challenges of this field for future research are presented. The research work indicates that the dynamic nature of trust creates the biggest challenge in measuring trust and predicting trustworthiness. So the future work will focus on the theoretical research of dynamic trust relationships to present a solid theoretical foundation for the practical applications.