Abstract: Electro-optical modulators are the core of optical communication links, and the pursuit of modulators with low half-wave voltages, large modulation bandwidths, low losses, and low fabrication costs remains the primary focus of modern optical communication system research.Currently, lithium niobate (LN) is the dominant material for modulator systems, but due to its low electro-optical coefficient, further improvement of device performance is challenging.Barium titanate (BTO), with an electro-optical coefficient more than 30 times that of LN, is a ferroelectric material of great significance for the study of electro-optical modulators.In this work, we systematically simulate, calculate, and optimize the optical and RF parameters of the BTO modulator using COMSOL, Lumerical, and HFSS software.The result is a BTO electro-optic modulator with a half-wave voltage-length product of 0.196 V·cm and a -3 dB modulation bandwidth exceeding 400 GHz at a device length of 1 mm.Overall, our study highlights the potential of the proposed modulator for low-drive-voltage, high-performance optical communication systems.