Pub/Sub systems can facilitate monitoring and managing objects for RFID applications. To fully support RFID applications, Pub/Sub systems should provide the means of subscribing RFID tags and the corresponding efficient matching algorithm. This paper provides the management mechanism and matching algorithm for primitive subscriptions whose specification permits to subscribe RFID codes. Our approach organizes clustered subscriptions into a covering forest and then executes primitive subscription matching on the basis of multi-level predicate indexes. Experiments are also conducted to evaluate the performance and overhead of our algorithm.