Abstract: To deal efficiently with imprecise and uncertain data associated with structural parameters and exciting loads, a multilevel control method was presented for vibration control of structures based on phase plane analysis. The phase plane was divided into many local grid regions, and the trajectory point corresponding to any instantaneous motion state of the controlled mass could be mapped to a grid region. The control force was obtained by distinguishing the motion trend of the controlled mass. Effectiveness of the proposed algorithm was demonstrated through a numerical example which considered a three-storey structure controlled with the active tendon system (ATS) installed in the first storey. Numerical results show that the proposed algorithm results in significant decrease in the seismic response of the structure when compared to the uncontrolled case, and the control performance of the algorithm is also superior to that of the linear quadratic regulator (LQR) algorithm.