The psychological behavior characteristic(PBC) of decision makers plays an important role in the evolutionary path and ultimate outcome of conflict. In order to describe the PBC of decision makers(DMs) in conflict, the stability theory is studied which considers DM's aggressive, conservative and balanced behaviors when facing risks based on the framework of the graph model for conflict resolution. Firstly, the reachable matrices are defined for the three PBCs. Then, the matrix representation for one and two-step stabilities are developed, respectively, for the stability or equilibrium calculation of DMs having different PBCs. This theory can facilitate the solution of the conflict when considering DM's PBCs and the development of the relevant module in decision support systems. Finally, the equilibrium outcome of environmental pollution conflict is analyzed by using the stability theory which considers the PBC of DM's under the framework of graph model. The results show that the proposed theory is effective and reasonable.