In the multi-agent supply chain of manufacturing enterprise, there is the problem that purchasing agent need negotiate with supplier agent about price. Based on analyzing the multi-agent collaborative framework, this paper presents a price-negotiating model, and discusses the negotiating tactics and steps between purchasing agent and supplies agent. And then an example is discussed for validating the negotiating model. This model is useful to optimize the supply chain management of manufacturing enterprise. Manufacturing enterprise and strategic partnerships may share profit and achieve joint gains based on this model.