Construction Industry has always been reputed by its high incident rates and poor safety performance. Construction accidents are, in most cases, resulted from the unsafe behaviors of construction workers on site. The study of workers' behavior is crucial in order to understand the causation of unsafe behaviors. Therefore, the objective of this paper is to simulate construction safety behavior in order to predict the number of safety incidents and better understand their causation factors. The simulation model illustrates how construction system influences construction labors on site in terms of unsafe behavior. The standard leading indicators of safety performance are first identified from the literature. Afterwards, a system dynamics model is developed to simulate the factors that affect safety behavior of workers on site. Furthermore, cellular automaton is introduced to account for the effect of safety climate/environment on workers' behavior, and thus, to study construction safety as an emergent behavior. The model involves dependencies among managerial factors as well as environmental conditions and aims to serve as a tool for the simulation of various project and managerial decisions. A hypothetical project case study is used in order to test the model results as well as the dependencies between the dynamic variables.