The vibrational coupling between the nucleus and electrons is an important factor in determining the ultrafast charge transfer rate of DNA biological systems. However, in most typical DNA base pairs like the guanine-cytosine (G-C) base pair, the vibrational coupling of ultrafast coherent charge transfer has been largely ignored. Here, we simulate the nucleus-electron interaction in the coherent charge transfer of G-C using ab initio molecular dynamics and Ehrenfest dynamics. Interestingly, the charge separation of G-C exhibits clear periodic oscillations. The calculated molecular orbitals, non-covalent interactions, and transition density matrix have oscillations with a period of about 10 fs. The reason behind G-C coherent ultrafast charge transfer is elucidated by examining the regular fluctuations evolving with time of the electron coupling strength, reorganization energy, and free energy. Our research can be extended to longer sequences of biological bases, contributing to the design of flexible, lightweight, and efficient biological DNA detection devices.