The battery pack is the core component of a new energy vehicle (NEV), and reducing the impact of vibration induced resonance from the ground is a prerequisite for the safety of an NEV. For a high-performance battery pack design, a clear understanding of the structural dynamics of the key part of battery pack, such as the battery module, is of great significance. Additionally, a proper computational model for simulations of battery module also plays a key role in correctly predicting the dynamic response of battery packs. In this paper, an experimental modal analysis (EMA) was performed on a typical commercial battery module, composed of twelve 37Ah lithium nickel manganese cobalt oxide (NMC) prismatic cells, to obtain modal parameters such as mode shapes and natural frequencies. Additionally, three modeling methods for a prismatic battery module were established for the simulation modal analysis. The method of simplifying the prismatic cell to homogenous isotropic material had a better performance than the detailed modeling method, in predicting the modal parameters. Simultaneously, a novel method that can quickly obtain the equivalent parameters of the cell was proposed. The experimental results indicated that the fundamental frequency of battery module was higher than the excitation frequency range (0–150 Hz) from the ground. The mode shapes of the simulation results were in good agreement with the experimental results, and the average error of the natural frequency was below 10%, which verified the validity of the numerical model.