Using the first principles calculations based on density functional theory, we study the electronic band structure, the phonon dispersion, and the phonon density of states of the iron-based superconductor LiFeAs. The obtained ground state of LiFeAs is of the fluctuated antiferromagnetic order and partial structural relaxation. A comparson of phonon densities of states between in the striped antiferromagnetic ordering and in the nonmagnetic state indicates that the anisotropic spin interactions result in phonon softening of Fe and As atomic vibrations, thereby enhancing the electron-phonon coupling. As a result, the spin-phonon interaction plas an important role in the unconventional superconductivity.