Abstract: LiFePO4 (LFP) lithium-ion batteries have gained widespread use in electric vehicles due to their safety and longevity, but thermal runaway (TR) incidents still have been reported. This paper explores the TR characteristics and modeling of LFP batteries at different states of charge (SOC). Adiabatic tests reveal that TR severity increases with SOC, and five stages are identified based on battery temperature evolution. Reaction kinetics parameters of exothermic reactions in each TR stage are extracted, and TR models for LFP batteries are established. The models accurately simulate TR behaviors at different SOCs, and the simulated TR characteristic temperatures also agree well with the experimental results, with errors of TR characteristic temperatures less than 3%. The prediction errors of TR characteristic temperatures under oven test conditions are also less than 1%. The results provide a comprehensive understanding of TR in LFP batteries, which is useful for battery safety design and optimization.