Enhancing the efficiency of charge transfer in dye is one of the most important issues for developing highly efficient dye-sensitized solar cells. Herein, we use resonance Raman spectroscopy (RRS) to study the effect of bond type and electron-donating groups on intramolecular charge transfer (ICT) of dithieno[3,2-b:2′,3′-d]thiophene based dyes. All the dyes have the enhanced Raman shifts for the donor moieties at the identical positions, supporting the donor is involved in ICT. The density functional theory (DFT) calculation elucidates that the triple bond and the electron-donating groups enhance the ICT of donor for the first and third electronic transitions. This is consistently supported by RRS which shows enhancement thiophene bands for all transitions as well as selective enhancement of donor and triple bond bands when the third electronic transition is probed. This suggests that ICT is enhanced by quinoidal character mixed in π-conjugation bridge. This study shows the potential of TD-DFT and RRS for studying the relation of the structure and the enhancement of ICT in organic dyes.