As a promising technology for monitoring and tracing the product flows and human activities, Radio Frequency Identification (RFID) has received much attention within database community. Moving range query over RFID data streams is one of the most important spatio-temporal queries to support valuable information analysis. However, the uncertainty of the monitored object location challenges the query strategy. Novel models and methods are desired. In this paper, we propose a probability evaluation model in the RFID-enabled monitoring environments and discuss the query optimization techniques under the scenarios of triggered moving range query, which can also be applied into more situations. The extensive experimental evaluation verifies the efficiency and effectiveness of our proposed model and methods.