The invention discloses a mobile relay and a system and an adjacent region self-optimizing method thereof and belongs to the field of wireless communication. The method comprises the following steps: when the mobile relay finds that the speed of the train with the mobile relay is lower than a preset first threshold and receives the fact that a donor base station indicates that the coverage area of the donor base station can configure a dynamic adjacent region relationship in a broadcast message, an adjacent region relationship adding process is started; the mobile relay obtains the 2G or 3G adjacent region information of the donor base station through the broadcast message of the donor base station, and effective 2G or 3G adjacent regions are added into a self dynamic adjacent region list; the mobile relay establishes an adjacent region relationship with the 2G or 3G adjacent regions in the dynamic adjacent region list. Through self-sensing, self-measuring and information interaction between nodes, the mobile relay can automatically add the adjacent region relationship of LTE/3G/2G regions in a macro base station when the train pulls into a station and pulls out of the station. The whole process does not need artificial participation, and the operation and maintenance cost is reduced.