Abstract: Asymmetric information is an important factor for affecting supply chain coordination, and designing contract mechanism is a method of achieving coordination. The problem of contract mechanism designing under bilateral asymmetric information structure is investigated in this paper. More specifically, a supply chain is considered consisting of one risk-neural supplier and one risk-averse retailer who have their private information regarding the production cost and retail cost, respectively. In a decentralized setting, the supplier and the retailer both have motivations to conceal their private information for better performance. To realize the efficient incentives, the conception of benevolent principal is introduced,thus the whole supply chain can be seen as the coordination subject. By virtue of the idea of the AGV (d' Aspremont and Gerard-Varet) mechanism, the incentive transfer payments is designed and a bilateral asymmetric information model of supply chain using mean-variance (MV) approach is constructed. It is found hat when the retailer's risk aversion degree is in some range, the designed incentive transfer payments based on AGV mechanism can only reveal the private information of two parties truthfully, but can not ensure their ex post nonnegative benefits. In order to overcome this issue, an ex-post allocation rule is presented that associated with the proportion of the expected information rents, and design the corresponding compensation parameters. Combining the transfer payments and the compensation parameters, a contract mechanism is proposed.It shows that the contract mechanism can reveal the private information truthfully and ensure the expost reasonable profits if the retailer's risk aversion degree does not exceed the upper bound k_r. When the supplier and retailer reveal their information truthfully, the supply chain with more risk aversion retailer has lower optimal commodity trading quantity and supply chain performance. Finally, one numerical example is presented to examine the incentive effectiveness for information revealing and analyze the sensitivity of the risk aversion degree.Some theoretical basis and practical guidance for bilateral asymmetric supply chain management will be provided in our research.

Key words: supply chain coordination, bilateral asymmetric information, benevolent principal, AGV mechanism, risk aversion