We put forward an affective computing model which simulates the mass incidents with venting anger using emotion to drive behavior. The model is on the basis of agent-based intelligent computing theory combined with the emotional contagion and the cluster behavior theory. For simulating procedure of events, we lead in some agent properties such as emotional valence, emotional energy level, sensitivity, perception and so on. The simulation experiment verifies that the emotional contagion is an important factor to promote the event, further reveals the characteristics and evolution mechanism of the mass incidents with venting anger.