Busbar, busbar assembly and battery module

The utility model discloses a busbar, a busbar assembly and a battery module, and the busbar comprises a main body part, at least one positive electrode connecting piece and at least one negative electrode connecting piece, the main body part comprises a water inlet, a water outlet and a flow guide channel which is arranged in the main body part and extends to the water outlet along the water inlet, and the flow guide channel is used for being filled with a liquid cooling medium; the positive electrode connecting piece is used for being connected with a positive electrode part of a battery, and the positive electrode connecting piece is electrically and thermally connected with the main body part; the negative electrode connecting piece is used for being connected with a negative electrode part of the battery, and the negative electrode connecting piece is electrically and thermally connected with the main body part. The busbar disclosed by the utility model is used for improving the heat conduction effect be