Disclosed are a frequency spectrum allocation method, device and system, so that a specific frequency spectrum allocation solution is provided for an application scenario of a multi-operator/perception system sharing a frequency spectrum. The method comprises: receiving first system throughputs which are reported by servers belonging to different operators and are determined by the servers on each frequency spectrum reference unit, wherein an available frequency spectrum is divided into a plurality of frequency spectrum reference units; and for each frequency spectrum reference unit, according to the first system throughput which is reported by the server of each operator on the frequency spectrum reference unit, allocating the frequency spectrum reference unit to the operator of which the value of the first system throughput is the maximum, thereby improving the usage efficiency of the available frequency spectrum.