The present disclosure provides a battery module and a busbar assembly thereof. The busbar assembly comprises a first busbar, a second busbar and a first insulator. The first busbar comprises a first connecting portion connected to a first battery unit, a second connecting portion connected to a second battery unit and a first main portion connecting the first connecting portion and the second connecting portion. The second busbar comprises a third connecting portion connected to a third battery unit, a fourth connecting portion connected to a fourth battery unit and a second main portion connecting the third connecting portion and the fourth connecting portion. The first main portion partially overlaps the second main portion, and the first insulator insulates the second main portion and the first main portion. The first battery unit, the third battery unit, the second battery unit and the fourth battery unit are arranged sequentially.