Human-computer negotiation plays an important role in B2C e-commerce. There is a paucity of further scientific investigation and a pressing need on designing the software agent that can deal with the human’s random and dynamic offer, which is crucially useful in human-computer negotiation to achieve better online negotiation outcomes. The lack of such studies has decelerated the process of applying automated negotiation to real world applications. To address the critical issue, this paper develops a strategy concession model.The theoretical model and algorithm of the combined strategy were developed. To demonstrate the effectiveness of this model, we implement a prototype and conduct human-computer negotiations over 121 subjects. The experimental analysis not only confirms our model’s effect but also reveals some insights into future work about human-computer negotiation systems.