網路購物成為生活中不可或缺的一部分，消費者購物型態也跨足線上零售平台以及實體商店，現今電子商務有別於以往扮演單純販售商品的媒介，而是透過網路平台給予製造商與消費者直接溝通的管道，也成為第三方保障消費者與製造商之間買賣交易的重要角色，然而製造商也會伴隨線上通路較實體店成本上的優勢，建立自己的直售通路與下游零售商競爭，對於零售商利潤影響巨大，本研究以網路銷售為出發點，探討當製造商侵蝕零售商利潤時，如何選擇其銷售策略及定價對於製造商與零售商有何影響，成為本研究感興趣的議題。
本研究假設市場中存在單一製造商與零售商，而製造商是否建立直售通路以及銷售模式的差異，我們可以建構出四種模型情境，分別為模型NR：單一零售通路之轉售模式；模型NM：單一零售通路之平台銷售模式；模型DR：雙通路下之轉售模式以及模型DM：雙通路下之平台銷售模式。而消費者對於產品的價值以及通路結構的不同具備異質性，將根據效用函式選擇適合自己的消費方式。
透過數值分析觀察直售通路成本以及效用折扣因子對於供應鏈成員價格決策、需求量與利潤的變化，發現到平台銷售模式不僅能使得消費者以較低的價格購買產品，還能降低雙重邊際化效應的影響增加供應鏈的效率，並且當直售通路成本相對較高且消費者對於直售通路存在差距時，儘管製造商建立網路直售通路，雙通路模式能消除侵蝕效應對零售商帶來的負面效果，還能為雙方帶來雙贏的局面。

Shopping online has become an indispensable part of our life. Customers purchase products through not only traditional retail channels, but also online channels. Nowadays, e-commerce is different from purely selling merchandise in the past. It provides manufacturers and customer with online platforms and becomes an important role for third parties to protect transaction security. However, due to the cost advantage of online channels, manufacturers also establish direct channels to compete with downstream retailers and to attract more customers. It hurts the retailer profits in this situation. As a result, how to select sales mode in different channel structure affecting members of the supply chain is an important issue.

This study considers a single manufacturer and online retailer in vertical supply chain. Whether there is a direct channel or not and combined sales mode differentiation, we can construct four model situations in our study. Besides, customers have a heterogeneous production valuation and channel preference. They will choose the appropriate channel and reasonable price to buy the product according to their utility function. The numerical analysis revealed that customers can purchase products at a lower price because the reduction of double marginalization and the efficiency improvement under marketplace mode. In addition, when direct cost is relatively high and the gap between the dual channel is significant, it could benefit the retailer with encroachment in certain threshold. Our results may eliminate negative effects caused by establishing direct channels.

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