<p style='text-indent:20px;'>In launching new green product or responding to market environment change, supply chain firms need to pour attention to best retailer's channel structure policy and coordination conditions. We consider a retailer-led green supply chain, and investigate optimal retailer's channel structure policy and supply chain coordination considering the impact of channel purchasing cost. First, we analyze three potential channel structures of green supply chain: offline channel structure (F), online channel structure (N), and dual-channel structure (D), and provide three functions to describe market demands for potential channel structures by analyzing the impacts of price, channel purchasing cost, and product greening level. Then, we develop profit functions and construct three joint pricing and product greening level optimization models to determine optimal joint optimization policies for structures F, N, and D, respectively. Furthermore, we conduct the theoretical analysis of retailer's channel structure selection, and provide numerical studies to illustrate and testify the theoretical results. Finally, we use a two-part tariff (TPT) contract to realize green supply chain coordination for structures F, N, and D, and show coordination conditions. Our research results indicate that, the optimal retailer's channel structure from each perspective is generally not uniquely determined, and optimal retailer's channel structures from three perspectives of manufacturer, retailer, and supply chain can be affected by channel purchasing cost, greening cost sensitivity, and preference degree of consumer to online channel.</p>