The invention discloses an emergency electronic ballast, which comprises a ballast circuit and an emergency circuit. The emergency circuit comprises a control circuit, a charging circuit, an inverter circuit and a switch circuit; the control circuit controls the work of the charging circuit, the inverter circuit and the switch circuit; utility power charges a rechargeable battery through the charging circuit; the ballast circuit is connected with the utility power through a switch; the emergency circuit supplies power after the inverter circuit is connected with the rechargeable battery and the voltage is boosted; the switch circuit switches on one of the ballast circuit and the inverter circuit so as to lighten a lamp tube; a sampling circuit is arranged between the ballast circuit and the emergency circuit, samples the utility power supply condition and the output condition of the ballast circuit and transmits signals to the control circuit respectively; and the control circuit controls the switch circuit to switch on one of the ballast circuit and the inverter circuit according to the sampled signals. Therefore, the emergency circuit is only started to lighten the lamp tube under the condition of needing emergency lighting, and the loss of the lamp tube due to error emergency is avoided.