Abstract: With the popularity of the Internet, the trend of online shopping is unstoppable, and the tourism industry has begun to try to provide customers with online ordering services to increase sales. Tour operator(TO) needs to spend a lot of manpower and material resources to open a new online travel website, while online travel agency(OTA) can hardly guarantee service differentiation under existing costs, which shows that TO and OTA are difficult to achieve results in the O2O model based solely on their own resources. Therefore, TO and OTA need to cooperate to create the O2O model. And OTA and TO can use the superior resources of both sides to complement each other. It is worth mentioning that the tourism promotion is very common and diverse. However, the existing literature lacks quantitative research on the level of tourism promotion efforts, and the existing research does not consider the linear change of TO's bargaining power. Therefore, in this paper, pricing strategies of tour operator(TO) and online travel agency(OTA) in promotion model are studied, and OTA provides online bookings for consumers, for which TO needs to pay OTA commission and provide travel services to customers who have already made online reservations. And The Nash bargaining model is constructed, in which, the TO's bargaining power is linear. In order to facilitate research, the model contains only one TO and one OTA. Firstly, the optimal pricing strategies are derived when TO bears the promotion cost, and then further the cost sharing contract is considered and the impacts on commission and promotion efforts are studied. The results show that the unit sale commission and OTA's profit decrease with TO's bargaining power, but TO's bargaining power has a positive impact on the promotion efforts, sale price, and the TO's profit. What's more, from the perspective of the profit of TO and OTA, whether the basic model or the impacts of cost sharing model is better depends on the value of the proportion of promotion cost, which is consistent with the actual situation. The promotion under the O2O model in the tourism industry is discussed, which has guiding significance for the cooperation strategies between TO and OTA.

Key words: O2O model, Nash bargaining, promotion, pricing strategies