Abstract: A joining element and joining method thereof are provided. The joining element comprises a head section, a rib section, and a tip section, wherein each cross section of the tip section has a geometric shape, and the geometric shape is formed by overlapping a plurality of ellipses. When the joining element applies downward pressure and rotational force on an assembly component, an inner concave portion of the geometric shape generates more plastic deformation heat than fraction heat on the material of the joining element. It facilitates the softening of the material in the assembly component, allowing for greater plastic deformation and, in turn, improves the assembly efficiency.