Abstract: Task allocation and evaluation decision approach have significant impact on supply chain management. A supply chain with hybrid structure is developed using contract net-based multi-agent system (MAS). The improved contract net-based bid model is presented through by introduction of relationship net and improvement of negotiation strategy of contract net. The evaluation decision approach is explored through analyzing bid information. The correctness and effectiveness is validated by a case study，and the results shows that the communication volume，negotiation time and management cost are quietly decreased，the system resources are saved，and system efficiency is increased through the developed system. Moreover，the supply chain with multi-agent system has better expansibility and reconfiguration.