The digital controller model of the primary mirror control system in an 8 m segmented ring solar telescope (8-m-RST) is established. The relationships between the sampling period, relative stability, integral gain and the control bandwidth are obtained by means of the extraction of the frequency characteristic parameters from the system model. In addition, with the introduction of a pulsed wind disturbance model, the performance of the primary mirror system under the disturbance of a pulsed wind with a low average speed is tested by simulation. The research results show that, the primary mirror control system in the 8-m-RST is stable and its control width meets the requirement of 0.2 Hz. Moreover, it can effectively suppress the disturbance from a wind with an average speed of 2 m·s -1. These results have important references to the structural improvement and the design of the tilt sensor and the controller in the 8-m-RST.