Abstract: In multiuser MIMO communication networks, a new amplify-and-forward two-way relaying scheme is proposed employing OFDMA for the multiple access transmission in the first time slot and OFDM/SDMA for the broadcast transmission in the second time slot to improve the performance of the system through utilizing frequency diversity and spatial diversity. Considering the characteristic of two-way relaying, the relay beamforming matrixes are designed according to two methods respectively, i.e., signal to leakage and noise ratio (SLNR) and block diagonalization based zero-forcing (BDZF), on per subcarrier basis. The upper bound on the capacity region of this two-way relay network is also derived by using cut-set theory. Simulation results show that the proposed scheme outperforms three other two-way relaying schemes in terms of sum rate and can approach the upper bound of capacity region.