Abstract: In the presence of a gray market, brand owners face significant challenges, including sales diversion, brand image erosion, and decreased market trust. Selecting an appropriate sales strategy to optimize decisions and improve profits is crucial. This study considers a two-stage supply chain consisting of a brand owner that simultaneously sells two complementary products and a gray market speculator. A two-stage sequential game model with the brand owner as the leader is constructed. In addition, four sales strategies are investigated, focusing on the effects of product complementarity, market potential, and the gray product discount coefficient on brand owner′s profits and optimal strategies. Results indicate that when the potential scale difference between the two complementary products in the high-priced market is significant, product complementarity is low, and the gray product discount coefficient is high, the brand owner should implement a pure bundling sales strategy in the low-priced market and a separate sales strategy in the high-priced market. Otherwise, a separate sales strategy should be employed in the low-priced market and a pure bundling sales strategy in the high-priced market.