Abstract：This study analyzed the winning strategies of professional Taiwanese women's doubles tennis players Yung-Jan Chan and Hao-Ching Chan (the Chan sisters) on server or receiver games. In order to identify and promote the integral elements of optimal performance, the information is provided for reference to tennis coaches and players. The research objects were 12 tournaments participated by the Chan sisters from 2015 to 2018. Totally, there were 24 players in these matches. Video recordings of the matches were analyzed with expert input from national coaches. Each hit was labeled by design factors and levels using the ＂larger-the-better＂ (LTB) signal-to-noise ratio (S/N), as described in the Taguchi method of optimizing processes. Results indicated that the best winning strategy for the service game is for Yung-Jan Chan to be the server. The first serve lands in and close to the opposite receiver's location. Her partner in front of the net, Hao-Ching Chan, quickly finds the chance to poach towards the opponents' no-man's-land and score. Their best winning strategy for the receiver game is for Yung-Jan Chan to be the receiver who returns second service diagonally. Hao-Ching Chan then finds an opportunity to poach towards the opponent's body and score. This study concludes that the Chan sisters' position of competition model is for Yung-Jan Chan to stand on the baseline and Hao-Ching Chan to find the chance to poach. Yung-Jan Chan is mainly attacking, creating chances for Hao-Ching Chan to score points. (Full text)