A polarization-independent electro-optical modulator based on thin-film lithium niobate (TFLN) is proposed; it is based on a polarization-independent beam splitter and a mode converter. The polarization-independent beam splitter achieves precise beam splitting of TE₀ and TM₀ modes, whereas the mode converter efficiently converts the input TM₀ mode to TE₁ mode. Accordingly, the traveling-wave electrode structure loaded with periodic capacitors achieves efficient electro-optical modulation of two light modes. The simulation results show that the electro-optical bandwidth of the modulator is greater than 100 GHz. This helps solve the instability problem caused by polarization sensitivity in existing electro-optical modulators and opens up new research lines for TFLN-based modulators.