A spectrum allocation method, device and system are provided, which are capable of improving the flexibility and applicability of the frequency spectrum allocation system. The spectrum allocation method includes: a proxy server obtains a frequency spectrum allocation policy thereof; the proxy server obtains the frequency spectrum resources of the area managed by the proxy server from the frequency spectrum resources of the area managed by the database; the proxy server receives a frequency spectrum resource request transmitted by an access device; and according to the frequency spectrum allocation policy, the proxy server allocates at least one segment of the frequency spectrum resources for the access device from the frequency spectrum resources of the area managed by the proxy server; and the proxy server transmits to the access device the frequency spectrum resource information including the at least one segment of frequency spectrum resource.