Molecular dynamics (MD) simulations have been performed for the spinel solid-solution, LiCoyMn2-yO4 in combination with experimental methods, X-ray diffraction (XRD), and infrared spectroscopy. The partial ionic potential model was used and optimized in the present MD simulation study. It showed good accordance with the observed lattice parameter on various Co contents and temperature. From the analysis of simulated results, it was concluded that the local distortion was caused by the mismatch of ionic size between Mn3+ and Mn4+ via the 16c vacancy site, and the Co substitution suppressed the local distortion in the lattice. The dynamical properties based on the simulated results were also analyzed and compared with experimental infrared absorption spectra. The reinforcement of chemical bonds by Co substitution was indicated in the simulation results, and it was supported by infrared absorption spectra.