Abstract: With the rapid development of the third-party logistics industry, the competitive advantage of the third-party logistics service provider (TPL) is increasingly prominent in terms of operation scale, integration services and information acquisition. This has driven fundamental changes of relevant economic forces in supply chain. How TPL's economic power change affects the decision-making and operation efficiency of upstream and downstream members of the supply chain is a kind of theoretical problem with research significance.Based on above background, this study aims to explore the influence of different power structures on decision-making and operational efficiency in a three-echelon supply chain including a supplier, a TPL provider and a retailer, to seek an effective path of improving system efficiency under each structure.Considering the endogenous wholesale price and the value-added logistics services, we develop two sequential non-cooperative game models are developed when the TPL provider and suppler act as leaders respectively. The game equilibrium solutions in above two models are proved to be exist and unique. Research shows that the total expected profits under two structures are lower than that in centralized setting. The retailer's ordering quantity, TPL's logistics service level and the ratio between them under TPL-led situation are lower than the corresponding results under supplier-led situation. Thus, TPL-led mode results in the lower system operational efficiency. With the TPL's profit structure as the starting point, we introduce logistics service fee sharing and cost sharing strategies into each structure, in order to improve the operational efficiency. Then, it is found that the influence of fee-sharing is suppressed when the supplier could manipulate the wholesale price, which leads to the failure of strategy in both two structures. However, the system operational efficiency can be improved and also the Pareto improvement can be achieved under logistics service cost sharing strategy in both two structures when the sharing coefficient satisfies certain conditions. Moreover, the optimal sharing coefficient depends on the expected profits of TPL and system without sharing strategy in each structure. Finally, a numerical example with the uniform distribution market demand is presented. With model SD and LD as the reference, the impacts of logistics service cost sharing coefficient on the decisions of each member, the expected profits and the system's total expected profits in model SDC and LDC after introducing logistics service cost sharing strategy into the system are mainly analyzed. It is found that:in model SDC and LDC, the optimal logistics service level and ordering quantity may be greater than those in centralized setting; The same sharing strategies do not have the same effects and the retailer need to share more of the cost of logistics service cost in model LDC in order to achieving the same operational efficiency; In SDC and LDC, the efficiency of the system can reach its maximum value at the expense of the retailer's interestwhich is inconsistent with the whole systemoperational efficiency in some cases.The conclusions of this paper provide the theoretical bases for exploring the influence of TPL-led mode on decision-making and efficiency of supply chain members and seeking effective approaches to improveoperational efficiency ofthe three-echelon supply chainwith TPL's participation.

Key words: power structure, Third-party logistics, three-echelon supply chain, sequential non-cooperative game, efficiency evaluation