Group-14 metalloles possess interesting optical properties and are promising molecules for light-emitting materials. We present a theoretical study of the electronic structures and the optical spectra from silole to stannole to gain insight into their optical properties. The optimized equilibrium geometries and the electronic and vibrational structures for the ground state (S0) and the first singlet excited state (S1) were calculated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT), respectively. The optical absorption and emission spectra were calculated using the thermal vibration correlation function formalism. The lineshapes of the calculated optical absorption and emission spectra, especially the full width at half maximum for all the compounds at room temperature, were found to be in od agreement with the available experimental data. Low-frequency modes that are assigned to the rotation motion of free aromatic rings and the high-frequency modes related to the stretching vibration of carbon-carbon bonds contribute greatly to the optical features such as the bandwidth of the optical line-shapes.