Based on density-functional theory (DFT) and wave function analysis procedures, the optical and molecular absorption properties of two structurally different pentacyclooxonium salt molecules have been investigated, and the physical mechanism of the formation of a built-in electric field due to orbital polarization caused by structural distortions, which induces charge transfer and leads to a nonlinear optical spectrum, has been explored.The properties result from the orbital polarization-induced built-in electric field driving charge transfer due to structural distortion. Theoretical analysis of ultraviolet-visible absorption spectroscopy (UV-vis) spectra is first performed to investigate the optical properties. The electronic excitation characteristics of the built-in electric field-driven charge transfer in molecules are analyzed in detail by transition density matrix (TDM) and charge differential density (CDD). Combining transition electric dipole moment density (TEDM) and transition magnetic dipole moment density (TMDM) analysis, the physical mechanism of the structure-induced chirality in their electronic circular dichroism (ECD) spectra is revealed. The results can provide theoretical references for the preparation of novel chiral materials as well as the research and development of optoelectronic materials and their practical applications.