Abstract: The amplifyandforward relaying strategy is investigated for the twoway relay equipped with multiple antennas in this paper. Firstly， the method of optimizations for relaying is derived based on the criterion of the minimum mean squared error with the full channel state information (CSI) at relay， which can achieve the optimal link reliability since both the uplink and the downlink are optimized by this strategy. Secondly， based on partial CSI and the channel statistics， two robust implementations， controlled by different parameters， for this optimal strategy are obtained for the scenario of the fixed relay but mobile users and that of the mobile relays， respectively. Simulation results show that the proposed strategies achieve quite good performances.