The invention discloses a frequency spectrum switching method in a distributed cognitive radio network. Cognitive users establish and maintain the own preferred frequency point neighbor list and a route cache list. When the cognitive users as the source nodes detect the authorized users, the cognitive users performs the following steps of: updating the own preferred frequency point neighbor list; judging whether available frequency point exists between the cognitive users and the next hop neighbor node, if so, selecting a first new frequency point according to the available frequency point and transmitting data on the new frequency point, updating the available frequency point in the preferred frequency point neighbor list to available frequency point around the first new frequency point, and updating corresponding neighbor node; and otherwise, combining the route caching list for switching frequency spectrum. The invention takes route factor into consideration according to characteristics of the distributed network cognitive environment, provides the specific frequency spectrum switching flow and signaling design thereof and ensures completion of frequency spectrum switch, thereby ensuring the persistence of communication of the cognitive users.