Abstract: An automated negotiation mechanism for resource allocation in grid is presented. The mechanism supports the dynamic adjustment and matching of the user's requirement and the resource service. In the mechanism, user's agent safeguards his interest. User's agent and resource gradually adjust theirs interest, change their requests to make the user's complex requirements match the resource services. This negotiation process is supervised by the negotiation-tunnel agent. At last, a simulation environment is established based on the GridSim toolkits and the simulation experiments indicate that the mechanism can eliminate the misfit between the user's requirement and the resource service, and can keep a fine efficiency within certain range.