A reconfigurable UHF RFID test system by adopting the virtual instrument and digital signal processing technologies based on the user-defined UHF protocol which also supports the ISO/IEC 18000-6C is proposed in this paper. The system can perform the protocol conformance test, and the measurement for multiple macro parameters such as modulation depth, response time, and bandwidth of RFID tags. The test results showed that the system can overcome the limitations of single standard and simulate the basic functions of the reader regardless of single tag or multi-tag identification. The system can be re-configured to support more protocols, easy to extend and integrate more features, quick and easy test.