The present disclosure provides a radio frequency spectrum management apparatus, method, system and secondary user apparatus for a cognitive radio system comprising primary systems and secondary systems, the radio frequency spectrum management apparatus comprises circuitry configured to: acquire, according to position variation information of respective secondary user groups in the secondary systems, path loss information at the positions before and after the movement of respective secondary user groups respectively, wherein, the secondary user group comprises one or more secondary users; and determine an adjustment to the usage of frequency spectrums of the secondary users, according to the variation of the path loss information at the positions before and after the movement of respective secondary user groups. The present disclosure may at least improve the efficiency of adjusting the frequency spectrum resource.