A system for avoiding mobile relay interference to a primary system on an authorized frequency spectrum, at least comprising: an available-spectrum information provision unit which communicates with the primary system of the authorized frequency spectrum, used to determine, based on operation information from the primary system, available-spectrum information of the authorized frequency spectrums that can be used in different geographical positional regions surrounding the primary system, wherein each of the positional region corresponds to at least one group of the available-spectrum information; a secondary system which communicates with the available-spectrum information provision unit, comprising: a base station; and an interference position determination module, used to determine, based on the available-spectrum information corresponding to different geographical positional regions provided by the available-spectrum information provision unit, at least one of the positional regions of the primary system which is being interfered by a mobile relay located within a coverage range of the base station, so that the base station could provide the determined positional regions for each mobile relay within the coverage range; and a mobile relay located within the coverage range of the base station, used to, when moving into the positional region determined by the interference position determination module, provide to the base station information containing the positional region where the mobile relay is located, so that the base station could adjust the mobile relay based on the at least one group of available-spectrum information corresponding to the positional region. an available-spectrum information provision unit which communicates with the primary system of the authorized frequency spectrum, used to determine, based on operation information from the primary system, available-spectrum information of the authorized frequency spectrums that can be used in different geographical positional regions surrounding the primary system, wherein each of the positional region corresponds to at least one group of the available-spectrum information; a secondary system which communicates with the available-spectrum information provision unit, comprising: a base station; and an interference position determination module, used to determine, based on the available-spectrum information corresponding to different geographical positional regions provided by the available-spectrum information provision unit, at least one of the positional regions of the primary system which is being interfered by a mobile relay located within a coverage range of the base station, so that the base station could provide the determined positional regions for each mobile relay within the coverage range; and a mobile relay located within the coverage range of the base station, used to, when moving into the positional region determined by the interference position determination module, provide to the base station information containing the positional region where the mobile relay is located, so that the base station could adjust the mobile relay based on the at least one group of available-spectrum information corresponding to the positional region. a base station; and an interference position determination module, used to determine, based on the available-spectrum information corresponding to different geographical positional regions provided by the available-spectrum information provision unit, at least one of the positional regions of the primary system which is being interfered by a mobile relay located within a coverage range of the base station, so that the base station could provide the determined positional regions for each mobile relay within the coverage range; and a mobile relay located within the coverage range of the base station, used to, when moving into the positional region determined by the interference position determination module, provide to the base station information containing the positional region where the mobile relay is located, so that the base station could adjust the mobile relay based on the at least one group of available-spectrum information corresponding to the positional region.