Real-time monitoring is an important function for manufacturing execution systems (MES). In order to acquire the real-time data information, RFID technology is used to collect the data in shop-floor. This paper studies RFID middleware for the real-time monitoring in discrete manufacturing. Firstly, a process flow model is proposed. And the model of the process flow is converting into a manufacturing node flow. Secondly, RFID devices are configured for the manufacturing node. And a formalized description for RFID middleware mode is suggested. For the sake of resolving the model of RFID middleware, the data process policy is studied, and the real-time status of the monitored part is acquired. At last, a prototypical software system is developed to demonstrate above ideas.