To investigate the thermal runaway propagation characteristics of lithium-ion power batteries, a two-dimensional heat dissipation model for a battery module incorporating phase change material (PCM) and an aluminum plate fin structure was developed. Employing ANSYS software, the study analyzed the thermal propagation characteristics of the battery module, considering scenarios where a pair of batteries in the middle of the module was induced to thermal runaway. The simulation results revealed that when the spacing between heat source batteries is narrow, the heat transfer is rapid and mutually influential, intensifying the propagation of thermal runaway and posing a significant threat to the safety of the battery system. However, when the spacing is wider, the intensity of thermal runaway propagation decreases, resulting in a relatively higher level of safety for the battery system.