The invention relates to a broadband-adjustable dispersion compensation device, comprising a fixed value dispersion compensation unit, an adjustable control unit, a selectable dispersion compensation unit and an output control unit which are connected in sequence, wherein the fixed value dispersion compensation unit is used for coarsely compensating optical signals; the adjustable control unit is used for selecting a proper module from the selectable dispersion compensation unit to realize high-accuracy dispersion compensation; the selectable dispersion compensation unit is used for providing modules capable of realizing high-accuracy dispersion compensation; and the output control unit outputs compensated optical signals. The invention also relates to a broadband-adjustable dispersion compensation method. The invention has the advantages of realizing adjustable dispersion compensation and obtaining higher compensation accuracy. Problems caused by optical fiber process errors and the slope index errors of a dispersion compensation module (DCM) are solved; elements for realizing a dispersion compensation function are not limited; and the device is simple to use and convenient to manage, thereby obviously improving the dispersion management efficiency.