A spectral electrotherapy device and a method of controlling the same are introduced, wherein a central processing unit provides a control signal for controlling the switching operation of an output driver to generate output voltage, thereby controlling output features of the spectral electrotherapy device. The control signal provided by the central processing unit to a switching unit uses central frequency f0 as a standard to thereby define the bandwidth of the central frequency f0 with difference Δf and define the points in time of the next change in the central frequency f0 and the difference Δf with first and second time intervals t1, t2, respectively. Values of the central frequency f0, the difference Δf, the first time interval t1, the second time interval t2 are generated from a dynamic parameter generating unit in different points in time. Electrical stimulation thus performed on the human body is complete and comprehensive.