The invention discloses an installation pin of a relay, a fabrication method of the installation pin and an installation structure of the ammeter base. The installation pin of the relay comprises a single thickening sheet body, wherein a window is formed in the thickening sheet body, a tongue sheet integratedly extends upwards from a bottom end of the window, the tongue sheet is provided with a thinning part relative to the thickening sheet body in a thickness direction so that the tongue sheet can generate elasticity, and the tongue sheet is bent outwards along a surface of the thickness of the thickening sheet body to form a withdraw prevention structure. The single thickening sheet body is used as the installation pin; and by improving the structure, the numbers of parts can be reduced, the processing cost of the parts is reduced, and the assembly process and the assembly cost are reduced.