Abstract: To further improve information transmission rate of wireless relay networks, an efficient downlink transmission scheme based on complex field network coding is proposed in this paper. Specifically, different from traditional information transmission scheme, the proposed downlink transmission scheme employs complex field network coding of time dimension, and each relay encodes the source symbols of multiple time slots received by complex field network coding, and transmits the encoded symbols to destinations simultaneously. Based on the data received from multiple relays, joint maximum likelihood multiuser detection is adopted at destinations to achieve the source symbols. Performance analysis and simulation results show that the symbol error probability (SEP) of the downlink transmission scheme is much less than the conventional relay transmission scheme. Moreover, the scheme can obtain higher information transmission rate and network throughput.