Abstract: In order to improve response and decrease the settling time, the structure response of the open loop system will be identified. According to the requirements of the structural dynamics performance of the control system, the design of the rotator control system is significant to improve the system performance. In this paper, a new method was proposed for the system model identification, the sin sweep signal was applied at the input of the open rate loop to excite the plant dynamic, the real time position feedback signal of the rotator was measured at the encoder, each frequency component of the rotator dynamics was analyzed to identify and obtain a meaningful transfer function, and in this article, the theory of the method was analyzed first, and the time series input is a sinusoidal sweep signal. The test of the system frequency response and the transfer function identification were realized through the testing experiment platform using this new method, the experiment chooses a controller designed by C8051F120 and CPLD, the output signal drives the rotator through the driver to verify this approach, and proving its feasibility.