在網路架構下的 first-price 買賣，加入了中介，這裡建構買家二階段的決策，並且探討買家的 連結數、 valuation 、連結成本、 bid 之間的關係。在本文中，中介對想要向中介連結的買家收取費用，接著找出最適的費用以及與其他變數之間的關係，接著在一些額外的假設下找出其配對方法。最後在不同買家 valuation 分配下發現變數間的關係是一致的。 / In buyer-seller network, on empirical premise, each buyer and seller must have a relationship, that is "link," to exchange a good. Each buyer should choose whether to link or not and choose how many links he or she should have. In this paper, we introduce an intermediary in the buyer-seller network. Buyers can construct links by themselves, or they can exchange through an intermediary. On the other hand, the intermediary also charges an entrance fee for its service. We then discuss the intermediaries' behavior and define the allocation rule. We find the intermediary allocation rule achieves maximal profit for the intermediary but this rule cannot reach the maximal total surplus. We also characterize the relationship between link cost, buyers' valuation, the optimal number of links, and the payoff of the buyer and intermediary.