Abstract: A control model identification method based on eigensystem realization algorithm (ERA), was proposed for the opto-electronic tracking turntable driven by a large power permanent magnet synchronous motor (PMSM). Firstly, the test configuration was designed based on the vector control theory of PMSM. Secondly, the frequency response function of the system was acquired through the power spectrum density function, which analyzed the sequence of the input and output data. Finally, to acquire the control model of the opto-electronic tracking turntable, the ERA was adopted to identify the Markov parameters of the control system. The experiment results demonstrate that the control model of the turntable can be identified accurately through the ERA, and the control model, which reflects the dynamics of the system better, can provide theory basis for the controller design. The results also confirm that the proposed method is practical.