Disclosure is a multi-voltage battery pack which includes: a housing, battery strings disposed inside the housing and including a plurality of battery cells, a battery interface disposed on the housing for use with the power tool, and a converting assembly disposed within the housing and electrically connected to the battery strings. The converting assembly has a first state, a second state, and a third state. The multi-voltage battery pack can separately output a first operating voltage, a second operating voltage, and a third operating voltage. The third operating voltage is greater than the second operating voltage, and the second operating voltage is greater than the first operating voltage.