Negotiation is a key issue for success application of multi-agent technology. According to the number of agents and the number of issues, negotiation in multi-agent environment can be classified as bilateral-single issue negotiation, bilateral-multi-issue negotiation, multi-lateral-single issue negotiation, and multi-lateral-multi-issue negotiation. The previous three scenarios are the simple forms of the multi-lateral-multi-issue negotiation. A multi-lateral-multi-issue negotiation model is provided to divide negotiation into processes,which are further divided into threads.The model defines a flexible negotiation protocol,which makes it easy to support differet negotiation scenarios.And the model also supports the learning capability of participating agents.