The invention relates to a method of pressing ghost waves of marine variable-depth cable earthquake data. The method comprises the following steps: firstly, transforming variable-depth cable earthquake data to a frequency domain; then, fitting frequency spectrum in the frequency domain, so that the difference between the frequency spectrum of the synthesized data and the frequency spectrum of the actually received data is extremely small, and the ghost wave pressing problem is transformed into a frequency spectrum fitting inversion problem. According to the characteristic of the variable-depth cable data, in an inversion process, a horizontal restrain item is introduced, so that the frequency spectrums on a trapped wave point position supplement with one another horizontally. The method of pressing ghost waves of variable-depth cable data disclosed by the invention is adopted, so that gradation is distinct; the transverse restrain item is adopted and a restrain factor is used to control the transverse restrain item, and therefore, the tapped wave effects of the ghost wave-pressed earthquake data are corrected in the frequency domain very well, the noises can be restrained very well in a time domain, and very good ghost wave pressing effects are achieved. The method disclosed by the invention can be directly used to a treatment process of acquired marine variable-depth cable earthquake data.