Electro-optic modulators based on lithium niobate (LiNbO₃, LN) thin-film platforms are advantageous for their small volume, high bandwidth and low half-wave voltage. They have important application prospects in the field of optical fiber communication and optical fiber sensing, and thus have became a heavily researched topic in recent years. In this paper, the research progress of the waveguide structures, coupling structures and electrode structures of LN thin-film modulators are reviewed in detail. The fabrication process of a LN thin-film waveguide is summarized, and the performances of different modulator structures are analyzed. Based on SOI and LNOI, a platform modulator is realized with V_πL<2 V∙cm, a bilayer inversely tapered coupling scheme achieves a coupling loss <0.5 dB/facet , and a traveling wave electrode structure achieves a modulation bandwidth >100 GHz. Thin-film LN modulators are better than commercial LN modulators in most aspects. It can be predicted that in the near future, with the further improvement in waveguide technology, thin-film LN will become a popular scheme of LN modulators. Finally, the potential directions for the future of their research are proposed.