Terahertz wave has the characteristics of high transmission rate, large capacity, good directivity and strong anti-interference ability, but it is more suitable for short-distance wireless communication due to the large atmospheric loss and the lack of high-power sources. Based on the excellent characteristics of the 300 GHz band, a 310 GHz terahertz wireless communication system is designed. The communication link is based on Virginia Diodes Inc(VDI) harmonic mixing and superheterodyne transmission. The system is mainly composed of frequency multiplier, power amplifier, filter and VDI subharmonic mixer. The actual communication system is built according to the link budget. The simulation and experimental results show that the distortion of the demodulated signal increases with the increase of the communication rate. The system can achieve 10 Gbps error-free transmission with a communication distance of 1 m. When the rate reaches 11 Gbps, the bit error rate is 5×10-6.