Abstract：Aiming at a supply chain with a seller and two e-commerce platforms, and based on Stackelberg theory, we focus on product pricing and promotion decisions under the mode of only platform promotion (A) and of both the seller and platform promotion (B) when different potential demand information sharing strategies are adopted by the platforms. The research shows that no matter under what kind of promotion mode, there is a positive correlation between the price of products and the promotion cost efficiency of supply chain enterprises. The entry of the seller’s promotion not only increases the profit of the platform without information sharing, but also increases its own profits which will reach the maximum when both platforms share information. In mode A, a lower demand forecasting accuracy and higher promotion cost efficiency make that only one platform tends to partially share information. In mode B, when promotion cost efficiency is low and information prediction is more accurate, both platforms will actively share demand information. However, when the seller’s promotion cost efficiency is higher, the case that only one platform shares information is more beneficial to the platform.
