In　the　e-commerce　transactions,　there　are　lots　of　commodities　with　the　same　name,　but　anyone　of　these　commodities　have　certain　attributes　which　differ　itself　from　others.　During　the　traditional　process　of　multi-agent　negotiation,　only　one　commodity　can　be　selected　as　the　negotiation　object　from　these　commodities　with　same　name,　if　buyer　agent　want　to　find　an　appropriate　commodity,　the　flexibility　and　efficiency　of　multi-agent　negotiation　would　be　low.　This　paper　studies　the　multi-agent　negotiation　model　by　argumentation　for　a　group　of　commodities.　It　firstly　defines　all　kinds　of　negotiation　elements,　then　establishes　a　negotiation　model　based-on　argumentation　and　describes　the　negotiation　agreements　and　strategies,　and　finally　an　example　would　be　presented　for　testifying　the　effects　of　this　model.