Abstract: This paper investigates the spectral efficiency (SE) and energy efficiency (EE) of a multi-pair two-way massive MIMO amplify-and-forward (MM-AF) relay system over Rician fading channels, where multiple user-pairs exchange information within pair through a relay with very large number of antennas. Firstly, the effect of hardware impairments on multi-pair two-way MM-AF system is taken into consideration and is modeled using transmit and receive distortion noises. Then, the zero-forcing reception/zero-forcing transmission (ZFR/ZFT) processing matrices of half-duplex relaying (HDR) and full-duplex relaying (FDR) are presented. Finally, the asymptotic s of the end to-end SINR are derived. Theoretical analyses and simulation results show that, the SE and EE of multi-pair FDR outperform that of the multi-pair HDR for the large relay antennas scenario. And as the signal-to- noise ratio (SNR) increases, the SE increases and saturates to a constant value. Moreover, when the number of relay antennas grows very large,the SE of MM-AF relay system is limited by the hardware impairments at the users instead of that at the relay or other interferences.