Abstract: A symmetrical joint structure for integrally joining a first joint element and a second joint element together, wherein the first joint element has a first joint portion and the second joint element has a second joint portion for intercrossedly joined with the first joint portion. Each of the first and second joint portion has two semi-conical engagement tongues fittingly engaged in two semi-conical engagement grooves of the other joint portion respectively, so as to integrally united the first joint portion and the second joint portion together to form the symmetrical joint structure.