The invention discloses a method for reconstructing frequency slot resources and relates to the technical field of an elastic optical network. The method comprises the steps as follows: monitoring all links in the elastic optical network, and judging if the frequency slot resources on the links meet the following two conditions at the same time: (a) Maxoccupied + Maxneed >= Sall; and (b) CA (i, j) / F (Sall - Soccupied) < Threshold; and if so, carrying out frequency spectrum shift on businesses on the links to integrate non-continuous frequency slot fragment resources on the links into continuous frequency slot resources. According to the method, the frequency spectrum resources are reconstructed, so that the utilization efficiency of the frequency slot resources can be improved and the business congestion can be reduced.