A dual-stage optical single side band (DSSB) modulation scheme to combat chromatic dispersion for the terahertz over fiber (ToF) systems application is proposed. In the scheme, terahertz wave is obtained via carrier-suppression double sideband (DSB) modulation, one sideband of terahertz wave then undergo the fisrt single sideband (SSB) modulation and the second baseband SSB modulation in the process of data modulation, which achieves cascade SSB modulation. As can ben seen from the sumulation result, for mid-frequency carrier of 0.1 THz, the bit error rate (BER) performance without dispersion compensation achives 1×10-11 and the sensitivity of the receiver is -26.6 dBm with a data rate of 5 Gb/s after 100 km transmission. Through comparing the power penalty of DSB and DSSB, we demonstrated the optical SSB modulation has better dispersion tolerance. This paper also shows the contrastive curves of frequency selective fading for the SSB and DSB modulated signals, which definitely demonstrates the existence of dispersion fading during the DSB transmission as well as the effective suppression of the fading implemented by the SSB modulation. The novel scheme′s preferences is excelled than the conventional scheme′s, which is demonstrated by these theory and simulation.