The invention discloses a lower base plate of a double-layer turnout vibration damping fastener and a manufacturing method of the lower base plate. The manufacturing method comprises the following steps that a, a steel plate is cut into a target size to obtain a substrate; b, a through hole is formed in the substrate, a first annular step is arranged at the top end of the through hole, and a firstannular chamfer or a first annular rounding corner is arranged at the bottom end of the through hole; c, a locking boss is prepared through a precision casting process, a second annular step matchedwith the first annular step is arranged on the locking boss, the bottom end of the locking boss is inserted into the through hole in the substrate, and the second annular step is tightly attached to the first annular step; and d, the locking boss and the substrate are fixed through a tool, joint filling and welding operation is carried out between the first annular chamfer or the first annular rounding corner at the bottom end of the through hole and the locking boss, and welding scar polishing operation is carried out after full welding. The lower base plate of the double-layer turnout vibration damping fastener comprises the substrate and the locking boss, wherein the substrate and the locking boss are connected in a welding mode.