In this paper,we introduce one full-duplex (FD) relaying transmission scheme for high speed railway and compare its ergodic capacity and outage performance with half-duplex (HD) relaying scheme.Both decode-and-forward (DF) amplify-and-forward (AF) relay modes are considered.Moreover,the carriage penetration loss (CPL) and the self-interference (SI) cancellation ratio are investigated.We derive the closed-form expressions for the outage probability and ergodic capacity of both HD and FD relay transmission schemes.It is shown that when CPL is larger than a certain level,the FD relay can achieve better performance in terms of capacity and keep the outage probability in a low level.It is also found that three factors:AF or DF modes,CPL and SI cancellation ratio,can have impact on capacity performance,and that CPL is one decisive factor.Our results can provide theoretical supports for development and deployment of future wireless communication systems on high speed railways.