Cross bar assembly and roof rack

The cross bar assembly comprises a first connecting structure, a second connecting structure and a connecting portion; the first connecting structure is connected to the roof guide rail, the first connecting structure is connected to the second connecting structure in a lockable manner, and the second connecting structure is connected to the connecting portion. The roof rack includes the cross bar assembly above, and the roof rack also includes the roof guide rail; when the first connecting structure locks the second connecting structure, the second connecting structure is mounted on the roof guide rail by using the first connecting structure, and the second connecting structure cannot be detached from the roof guide rail, and when the first connecting structure is unlocked from the second connecting structure, the second connecting structure can be detached from the roof guide rail, thereby preventing other people from stealing the cross bar assembly.