In recent years, the high-performance electro-optic modulator based on the thin-film lithium niobate (TFLN) platform has been receiving considerable attention due to the featuring small footprint and low energy loss. In this paper, a novel Y-junction electro-optic modulator with a vertical electrode structure was designed based on TFLN. The relationship between the low half-wave voltage and the buffer layer thickness for the novel modulator was investigated. Meanwhile, the design parameters of Y-junction were optimized, and found that the half-wave voltage is less than 1.5 V and the insertion loss is less than 5 dB. Finally, the Y-junction electro-optic modulator was fabricated. This study not only provides insights on the design and realization of compact footprint photonic waveguides in the TFLN platform but also, experimental evidence for the fabrication of electro-optic modulators with high-performance and multifunction.