Radio Frequency Identification (RFID) has gained a lot of attention as a promising technology that facilitates pervasive computing and the gradual proliferation of RFID-based applications will produce a large amount of urgent and complicated event streams. The RFID middleware system is expected to offer the further complex event processing service to satisfy the high-level query semantics and performance demands, and therefore, how to evaluate the service capability will be a key problem in mission-critical monitoring scenarios. In this paper, we analyze the RFID primitive event arrival and complex event processing model in a novel perspective. Furthermore, based on our proposed models, service capability evaluation method is introduced to estimate whether and how the RFID middleware system can afford the query requirements in a deterministic or statistical manner, which is believed to be very helpful in RFID-based applications. Our experiments demonstrate the utility and feasibility of our models and methods.