The invention belongs to a method for generating a single high-frequency side band millimeter wave signal by using a smaller-bandwidth intensity modulator and a lower-frequency radio-frequency signal The invention belongs to a method for generating a single high-frequency side band millimeter wave signal by using a smaller-bandwidth intensity modulator and a lower-frequency radio-frequency signalin the technical field of Radio-over-Fiber (abbreviated as ROF). The system makes full use of the reliability and low cost characteristics of double-side-band modulation and the excellent signal perfoin the technical field of Radio-over-Fiber (abbreviated as ROF). The system makes full use of the reliability and low cost characteristics of double-side-band modulation and the excellent signal performance and fiber dispersion of single-side-band modulation. At a central station, multiple double-frequency technology is adopted to generate high-frequency millimeter microwaves, so the requirementsrmance and fiber dispersion of single-side-band modulation. At a central station, multiple double-frequency technology is adopted to generate high-frequency millimeter microwaves, so the requirementsof the central station on element bandwidth are reduced and the configuration of the central station is simple and easy to realize, and the cost of the central station is reduced. A base station usesof the central station on element bandwidth are reduced and the configuration of the central station is simple and easy to realize, and the cost of the central station is reduced. A base station usesa filter to acquire a single-side-band signal having a bandwidth which is two times of that of the conventional single-side-band. Therefore, a higher direct current component at a central carrier wavea filter to acquire a single-side-band signal having a bandwidth which is two times of that of the conventional single-side-band. Therefore, a higher direct current component at a central carrier waveposition generated when the single-side-band modulation is used directly is avoided and the influence of the fiber dispersion on the signal is reduced. In addition, the method can filter the central position generated when the single-side-band modulation is used directly is avoided and the influence of the fiber dispersion on the signal is reduced. In addition, the method can filter the centralcarrier waves of the ROF millimeter waves from a down link and be used for reusing the wavelength of an up link, and simplifies the base station.carrier waves of the ROF millimeter waves from a down link and be used for reusing the wavelength of an up link, and simplifies the base station.