In order to evaluate the operational effectiveness of tear gas in handling large-scale crowd incidents,this study first establishes an evaluation index system for tear gas operational effectiveness based on its mechanism of action. Then, an ADC model for evaluating tear gas operational effectiveness is proposed and established. The model analyzes and computes the availability (A), credibility (D), and capability (C) in conjunction with the actual use of tear gas. Finally, the model is utilized to assess the operational effectiveness of tear gas in handling a large-scale crowd incident, and the results validate the effectiveness of the model.