The utility model relates to a busbar fixing device of a breaker, and a cover plate thereof, wherein the busbar fixing device of the breaker comprises a static contact, a base front bottom plate, a base rear bottom plate and a cover plate; the static contact is provided with a contact bridge which clamps the busbar; the base front bottom plate and the base rear bottom plate are connected to form a space containing the static contact; the cover plate is connected to the base rear bottom plate and provided with a square hole; the busbar passes through the square hole to be contacted with the contact bridge; the side wall of the square hole is provided with a fixing hole; the busbar is provided with a hole; and a fixing part passes through the aligned fixing hole and the hole to cause the busbar to be fixed in the square hole. The fixing device can prevent the busbar from dropping due to oscillation when the breaker is subjected to large current impact, thus avoiding accidents and effectively preventing the breaker from being damaged due to improper exertion when installing the breaker.