Wind-induced dynamic torque on rectangular cylinders with various side ratios is investigated through a series of model tests ina boundary layer wind tunnel. Based on the experimental investigation, this paper presents empirical formulae of torque spectra,RMS torque coefficients and Strouhal number, as well as coherence functions of torque. An analytical model of wind-induceddynamic torque on rectangular tall buildings is established accordingly. Comparisons of the results from the proposed model andthe wind tunnel measurements verify the reliability and applicability of the developed model for evaluation of torsional dynamicwind loads on rectangular tall buildings. A calculation method is presented based on the proposed model to estimate wind-inducedtorsional responses of rectangular tall buildings in the frequency domain.