Cellular Automata model was improved to simulate the herd behavior of people in case of exi- gency of social safety,in consideration of the influence and insistence of the behaviors.Starting with the initial state of uniformly mixed behaviors,the behavior groups were produced.As long as the propor- tions among the different kinds of behaviors are not far from equilibrium,the herd behavior can not lead to the state of only one behavior left and others dissipated,but to the state of many kinds of behaviors existing in the form of behavior groups.