Abstract: The research attention of MAS (multi-agent system) trust model is now focusing on the devising of trust mechanisms. But the macro properties implied by these micro mechanisms are not obvious. So, all of the researches apply modeling and simulation for analyzing the macro properties generated by trust mechanisms. However, lots of these simulation experiments lack proper guidance by simulation theory and sometimes can not exactly reflect the properties. This paper introduces the notion of emergence in system science to investigate MAS, and develops a simulation approach based on this notion for analyzing the MAS trust model. Starting with the relatively clear behavior of MAS micro level (i.e. agents behavior), considering sufficient MAS macro constraints, and building up a runnable simulation system, this approach studies the macro problems and the micro-macro relations of the MAS trust model. Accordingly in this paper, at the micro level, the design scheme of trust mechanisms is analyzed and summarized, and based on this, a framework for implementing simulation agent is proposed. At the macro level, several system issues that must be taken into account in simulation-based MAS analysis are discussed, including macro constraints, threat model, evaluating metric, and issues in simulation running. Finally, this method is validated via several simulation experiments.