IEEE 802.16 standard suite defines two main polling modes: unicast polling and contention-based polling. These polling modes are adaptively adopted by different service classes in order to guarantee different performance requirements from different applications, in which the nrtPS (non real-time Polling Service) service class is defined to allow to adopt both the two polling modes. However, the standard does not specify exactly how these polling modes should be used for nrtPS. In this paper, by simulation, we evaluate the performance of the different polling mechanisms. We present a fact that an optimal unicast and contention-based mixed polling mode for nrtPS could allocate the bandwidth more efficiently and achieve better performance.