The utility model relates to a battery box, specifically to a multifunctional battery box of a communication optical fiber cable fusion splicer. The multifunctional battery box is simple in structure, convenient to use, convenient for charging and suitable for field work. The multifunctional battery box is characterized in that a battery is disposed in a box body; the side wall of the box body is provided with a fusion splicer power supply interface and an alternating voltage input interface; an overcurrent detection protection module used for overcurrent protection, a level switching circuit used for converting voltage and a charging control module are disposed in the box body; the battery is connected with the fusion splicer power supply interface through the overcurrent detection protection module and the level switching circuit; and the alternating voltage input interface is connected with the battery through the charging control module. The multifunctional battery box is convenient to use, is high in endurance, and can be widely applied outdoors for supplying power to fusion splicers.