The Asymmetric information among different entities can contribute to the imbalance between supply and demand in agricultural supply chain. Negotiation is an effective method to address information symmetry. Many researchers can be found in the literature on agent-based negotiation in industrial supply chain, but very few in agricultural supply chain, primarily because of the interior instability. This paper presents an agent-based negotiation framework for agricultural supply chain to address the information symmetry by introducing the third party logistics. The third party logistics, with more functions than a traditional broker, integrates logistics services and intermediary services to guarantee the relative stability in dynamic agricultural environments. A negotiation interaction process is also designed to facilitate the interaction among these agents. Finally, a case is used to validate the proposed framework.