Aiming at the timely characteristic of emergency decision, a method of emergency decision for the large group based on the exit-commission dynamic conflict eliminating mechanism is proposed. Firstly, the decision group is clustered by preference, the group conflict degree is measured, and the conflict degree is judged. The conflict eliminating method is used when the degree is high. Then, an exit mechanism is proposed to make the cluster whose preference is high conflictive with group preference exit the decision-making process. The commission mechanism is used to make the cluster who exits the decision-making process influence the subsequent decision. The feedback mechanism is used to decrease the conflict degree. Finally, a numerical example is given to illustrate the rationality and feasibility of the proposed method.