An elbow joint device applied in goal includes: a first rotation component, a second rotation component and a junction plate. The first and second rotation components which can be inserted into the inner side of goal bar having a first and a second connection component are assembled in the junction plate. The first and second rotation components have a first and a second groove with a first and a second rotation hole passing through. The first and second rotation components pivot on the junction plate via bolts in the first and second rotation holes so that a goal can be unfold or fold by using the elbow joint device.