Abstract: Addressing the drawbacks of lead-acid batteries used in power plant DC power systems, such as short cycle life and the risks of hydrogen evolution and explosion, this paper investigates the application of novel sodium iron phosphate batteries. The charging and discharging mechanisms, along with technical characteristics including energy density, cycle life, and safety, are systematically analyzed. Furthermore, considering the load characteristics of power plants, a system integration solution combining a sodium iron phosphate battery pack with a Battery Management System (BMS) is proposed. Additionally, extreme condition tests—including high-temperature charging, low-temperature over-discharge, overcharging, short circuit, nail penetration, and combustion—were conducted to verify the outstanding electrical performance, safety, and reliability of the sodium iron phosphate batteries. Finally, the paper analyzes current challenges, such as an incomplete standards framework, and outlines future application prospects. This study provides a valuable reference for the application of sodium iron phosphate batteries in power plants.