Abstract: Online tourism supply chain is a typical super network. In this paper, an online tourism supply chain network equilibrium model is developed with three layers’ network structure of suppliers, platforms and demand markets, which compete each other no cooperatively to maximize their expected profits by determining their optimal product transactions. The consumers at the tourism demand markets reflect their preferences through the demand price functions, which depend on the tourism product demands and on the average level of the risk in the tourism network. It is demonstrated that Nash equilibrium conditions can be formulated as a variational inequality problem and describe the optimal economic behavior of the partners, and analyses the impact of the risk control investment on the risk level, expected profit of platform enterprises and the whole tourism supply chain. The modified projection algorithm is applied to compute solutions to a spectrum of numerical examples. The research outcome includes as following:Firstly, In case of the same risk control investment, the product transaction quantity and price between platform and market are almost the same, which verifies the rationality and effectiveness of the model. Secondly, while the increase of risk control investment the transaction risk of the platform decreases, as well as the transaction security level and transaction volume of the supply chain network increase, but the expected profit of the platform decreases. Finally the consumer profit benefits from the more platform involvement, but the free rider behavior of some of the platforms will lead to increase the overall supply chain transaction risk level.

Key words: online tourism supply chain, variational inequality, transaction risk, Nash equilibrium