In order to obtain reasonable aerodynamic shape of П shaped bridge decks, the buffeting performances comparison of a cable-stayed bridge was conducted based on wind tunnel tests. Firstly, three different types of П shaped bridge decks were designed based on one real cable-stayed bridge with a main span of 300 m. Secondly, force balance and vibration sectional model wind tunnel tests were carried out to obtain aerodynamic parameters under different wind attack angles. The aerodynamic parameters include three-component static wind loading coefficients, flutter derivatives, etc. Finally, three types of П shaped bridge decks' buffeting performances were compared and analyzed by considering the aeroelastic and buffeting forces. The results show that buffeting responses of the bridge with different П shaped decks are different from each other. Buffeting responses in any one freedom could be changed when changing bridge deck shape. However, the optimal influences in vertical, lateral and torsional directions could not be achieved at the same condition. Reasonable aerodynamic shape selection of П shaped bridge decks should consider the mechanical characteristics and the performances of flutter, vortex and buffeting.