The drag coefficients of Square Towers with Circular Members （STCM） in Reynolds number range from 307 to 906 are performed by wind tunnel test with section model. The effects of the solidity ratio， turbulence intensity， and wind speed on the drag coefficients are analyzed. Based on the experimental results， the applicability of three Reynolds Averaging Navier-Stokes （RANS） models in Computational Fluid Dynamics （CFD） for the aerodynamic force simulation of STCM is compared. The variation law and influencing factors of drag coefficients in the range of Re=300~2.5×104 are further analyzed. The experimental results show that the mean drag coefficient of STCM is maximum at 45° and minimum at 0° and 90°. The mean drag coefficient decreases with the increase in solidity ratio and wind speed and increases with the turbulence intensity. The fluctuating drag coefficient is not affected by the solidity ratio and wind direction angle but increases with the wind speed and turbulence intensity. The CFD results show that the SST k-ω model is more suitable for calculating the mean drag coefficient of STCM at Re≤2.5×104. With the increase of Reynolds number， the mean drag coefficient of the STCM decreases sharply at Re= 300~585， slightly slows down at Re=585~1 090， and remains basically unchanged at Re=1 090~2.5×104. Compared with the drag coefficient of upstream members， the values of downstream members completely immersing in the wake of upstream members can be reduced by about 50%.