Abstract: In order to make mutual coordination in the main process of steelmaking, continuous casting and hot rolling, improve the production plan level and enhance resource allocation benefits in steel enterprises, a unified model was applied to describe the rolling plan, charge plan and cast plan. Meantime, object functions during various plans were integrated from the perspective of universality to connect the production plan in each stage. The model was solved to make the integrated planning by a designed co-evolutionary algorithm based on a multi-agent system. Model test was performed in a steel enterprise according to its production plan, and the simulation results show that the model is effective.