The invention discloses a spectrum allocation method, an apparatus and a storage medium for a space division multiplexing optical network, wherein the method comprises the following steps: determininga plurality of alternative paths for transmitting a traffic stream; sequentially calculating the cores of all the fiber cores in each path segment; and calculating the cores of all the fiber cores ineach path segment. Spectrum two-dimensional resource available values and based on core Sorting the fiber cores from high to low order of spectrum two-dimensional resource available values; Selectingthe core as the candidate core in each path segment of the alternative path according to the sorting order, and taking the candidate core as the transmitting core if the continuous spectrum resourceselected in the candidate core satisfies the preset crosstalk requirement; Establishing a core transmission path for transmitting a traffic flow based on the transmitting core; The method, device andstorage medium of the present invention preferentially selects a core. The core with the largest available value of spectrum two-dimensional resources can be used to screen the continuous available spectrum resources, which can reduce the blocking rate of service and improve the utilization of spectrum resources, and improve the user 's perception of use.