Abstract: In order to meet the demand of future high-speed space communication, a high-speed wireless communication system at W band (75~110 GHz) was investigated. For solving the bottlenecks of bandwidth-constrained electrical components, the communication system adopted photonic up-conversion technology to generate 20 Gbit/s W-band quadrature phase shift keying (QPSK) signal. At the receiver, analog down-conversion and advanced digital signal processing technology were adopted to realize the off-line signal demodulation after 360 m wireless transmission. The bit error rate (BER) of the system is less than the hard-decision forward error correction (HD-FEC) threshold of 3.8×10?3.