In this paper we introduce a wireless communication system based on NI USRP and RTLSDR.Its software characteristics and hardware framework are analyzed.Taking FM modulation and demodulation method to send and receive audio signal as an example,using the digital quadrature modulation and demodulation algorithm,NI USRP is used as transmitter, RTLSDR as receiver,and the signal and data will be processed in Simulink block diagram in PC. The implementation procedureand test results are presented.The experimental results show that the designed system can send the received audio signal better.