The invention discloses a method and system for evaluating the dam-break risk of a dammed lake based on a negotiable and cooperative work flow, which are used for the negotiable and cooperative evaluation of the dam-break simulation and influence analysis of the dammed lake. The system is characterized in that a distributed frame based on a four-layer system is adopted. The system consists of three parts: a moving Agent, an AgentHost and a cooperative Agent. In the invention, the centralized decision and treatment of disaster negotiation information are accomplished by providing cooperative virtual work environment of multiple point in different places, command and decision makers and related personnel at all levels in different regions can cooperatively communicate to share and exchange disaster information and take part in discussion about the dam-break simulation and the influence analysis of the dammed lake together, and the cooperative analysis and the evaluation of the dam-break risk of the dammed lake are achieved. The invention has the advantages of simple method and high execution efficiency, is suitable for multiple users distributed in different places to carry out negotiable and cooperative evaluation, and can effectively improve the work efficiency of the dam-break risk evaluation of the dammed lake.