Aiming at the heat dissipation requirements of future high-power batteries under complex operating conditions, this paper adopts immersion flow boiling as the strategy to investigate battery thermal management performance under Nürburgring circuit condition of Porsche Taycan. A multi-filed coupled model is proposed to investigate its flow and heat transfer performance. The results show that batteries have a higher heat generation in non-steady conditions, which means that it is more crucial to investigate the battery thermal management performance under non-steady state. Immersion flow boiling can meet the thermal management requirements of batteries with high heat generation rate, which has significant advantages over single-phase liquid cooling, and the temperature uniformity can be further improved by means of roughing surface. Besides, flow velocity will completely change the heat transfer and flow mechanism of immersion flow boiling. The optimum flow regime can both exchange heat by liquid–vapor phase change and replenish the vaporized working medium by convection, achieving the lower temperature rise and better temperature uniformity in battery. Moreover, the boiling heat transfer in battery thermal management is in the partial nuclear boiling state, which is much lower than the critical heat flux, and thus can effectively inhibit high heat flux conditions such as thermal runaway.