Abstract: The multiplex transmission of orbital angular momentum (OAM) is a new radio transmission technology. In this paper, the radiation characteristics of a single-feed point annular microstrip rectangular patch antenna are used to generate a C-band OAM helical beam, and a ring OAM array antenna is fabricated. To verify the transmission performance of the OAM array antenna, the OAM antenna is combined with the Universal Software Radio Peripheral (USRP) to build an OAM wireless transmission system using Software Defined Radio (SDR) technology. The experimental results show that the system can realize real-time transmission of audio signals in real channel environment. Because the OAM multiplexing transmission technology has the advantages of good transmission security and high spectrum utilization rate, so the construction of OAM system has certain practical significance in wireless communication, and it has potential application in the future communication field.