To investigate the complex wind environment around the tower of long span railway-highway combined cable-stayed bridge, the computational fluid dynamics (CFD) was employed to simulate the wind field above the highway deck around the tower. Based on the wind tunnel test of large scale local rigid tower-girder model the wind speed measurements at the center height of three typical highway vehicles and train were conducted, respectively, and the wind speed coefficient λ, wind speed mutation rate ξ and the wind speed fluctuation rate η were introduced to analyze the average wind speed variation and the instantaneous wind speed fluctuation. Results showed that a certain wind speed acceleration effect was observed in the flow field near the tower. The degree of wind speed variation at different heights above the deck was different, and the change of flow at center height of the medium-sized coach was more intense. Wind speed at upwind side was greater than that at downwind side, but the wind speed gradient at downwind side was larger. Due to the wind shield effect of the tower, the influenced area of the average wind speed was about 3 times the width of the tower windward surface, and that of the instantaneous wind speed fluctuation was slightly less than 4 times the width of the tower windward surface on the highway deck, whereas it was slightly larger than 4 times the width of the tower windward surface on the railway deck.