Abstract: The long-term vibration monitoring has been carried out in one 120 m single-tube steel tower and one 120 m steel-concrete hybrid tower of 2.0 MW wind turbines in the same wind farm. The modal parameters of both towers are identified and analyzed by peak picking method（PP）and random subspace method（SSI）respectively and then compared with the numerical analysis results. It turns out that the first three vibration modes play a dominant role in the vibration of the two towers,and the influence of the high-order vibration modes cannot be ignored. Compared with the steel-concrete hybrid tower,the full steel tower is more easily affected by the rotation of the rotor at the top of the tower,and so that the resonance is more likely to occur. The aerodynamic damping in the modal damping is relatively large and greatly affected by the ambient wind speed and the pitch angle,which has nonlinear relationship with the wind speed and significantly changes as the pitch angle changes. Comparing the measured results with the numerical analysis results,it can be found that the measured modal frequencies of both towers and the measured mode shapes of the hybrid tower are all well consistent with the numerical analysis results,while the measured mode shapes of the full steel tower are different from the corresponding numerical results,in which the more attention should be paid in operation and maintenance.