The invention provides an emergency power supply system. The system comprises a battery pack, a monitor, a first controller and a frequency converter, wherein when alternating current (AC) information acquired by the monitor indicates AC supply stops, the monitor triggers the first controller which controls the battery pack to output a direct current (DC); and the frequency converter inverts the DC into AC and sends the AC to a working pump in an oil pump unit. In the emergency power supply system, by acquiring the AC supply information, when the AC supply stops, the battery pack is started to output the DC which is inverted into the AC and then the AC is sent to the working pump in the oil pump unit, thus providing a safe emergency power guarantee for large diffusions of blast furnace tops, hot blast heaters and other important blast-furnace equipment, and solving the technical problem that human safety and production safety are harmed seriously because a blast furnace system is in a dangerous state even explodes, which is caused by the factor that required emergency powers cannot be provided for the blast furnace system in time when the AC supply stops in the prior art.