Graphene has shown promising perspectives in optical active components due to the large active-control of its permittivity-variation. This paper systematically reviews the recent developments of graphene-based optical modulators, including material property, different integration schemes, single-layer graphene-based modulator, multi-layer and few-layer graphene-based modulators, corresponding figure-of-merits, wavelength/temperature tolerance, and graphene-based fiber-optic modulator. The different treatments for graphene’s isotropic and anisotropic property were also discussed. The results showed graphene is an excellent material for enhancing silicon’s weak modulation capability after it is integrated into the silicon platform, and has great potentials for complementary metal oxide semiconductor (CMOS) compatible optical devices, showing significant influence on optical interconnects in future integrated optoelectronic circuits.