By adopting wind tunnel model tests with synchronous pressure measurement, the aerodynamic force and wind response characteristics of diagonal twin towers under different spacing and wind directions were investigated from the perspectives of structural wind load and wind-induced acceleration, which is expected to provide reference for the wind-resistant design of diagonal twin towers. Results show that there were two most unfavorable wind directions in terms of wind responses: diagonal direction (around 45°) and near tandem arrangement direction (around 80°). In the wind direction of around 45°, the diagonal twin towers experienced remarkable across-wind oscillations caused by vortex shedding. However, due to the aerodynamic interference between the two towers, these across-wind oscillations were smaller compared with the single tower under the same wind conditions. Moreover, the favorable aerodynamic interference was more evident on the upstream tower than on the downstream tower. In the wind direction of around 80°, the downstream tower was excited by the wake of the upstream tower, which might result in severe wake-buffeting in the across-wind direction. The across-wind oscillation due to vortex shedding in around 45° wind direction mainly occurred at a subcritical to critical wind speed of vortex-shedding, and the wind speed was relatively low. The critical wake-buffeting under a wind direction of about 80° mainly occurred at supercritical wind speeds, and the wind speed was relatively high. Since the design wind speeds for super-tall buildings are mostly lower than or close to the critical wind speed of vortex shedding, the control of the across-wind oscillation for wind direction of about 45° is the key to wind resistance design. In this case, it is beneficial to designing diagonal twin towers with smaller spacing.