This paper deals with the along wind dynamic response of tall buildings passively controlled by Cross Tensioned Spring Damper (CTSD) mechanisms. In order to estimate the dynamic response more accurately and efficiently, the building and its CTSD controllers were considered as a coupled non classical damping system and a new stochastic response analysis method, complex modal state space method, was proposed based on the combination of complex modes of the structural system rather than on the real modal decomposition as usual. As numerical examples, the displacement response of a 2 degree of freedom system to white noise input is first considered and the validity and accuracy of the proposed method are demonstrated through comparison with the exact results. The wind induced dynamic responses of a tall building controlled by two CTSD mechanisms are then analyzed. The calculation results showed that the proposed method is much more appropriate and accurate than the conventional real modal decomposition method in the analysis of dynamic responses of passively controlled tall buildings. This paper deals with the along wind dynamic response of tall buildings passively controlled by Cross Tensioned Spring Damper (CTSD) mechanisms. In order to estimate the dynamic response more accurately and efficiently, the building and its CTSD controllers were considered as a coupled non The system and a new stochastic response analysis method, complex modal state space method, was proposed based on the combination of complex modes of the model system rather than the real modal decomposition as usual. As numerical examples, the displacement response of a 2 degree of The calculation of the results of the proposed method is demonstrated by the validity of the proposed method and the validity and accuracy of the proposed method are shown by the validity and accuracy of the proposed method are disclosed through comparison with the exact results. The wind results in the The proposed method is much more appropriate and accurate than the conventional Real modal decomposition method in the analysis of dynamic responses of passively controlled tall buildings.