The utility model discloses a device of control bridge pier column cover to reinforcement thickness belongs to municipal engineering construction technology field. The utility model discloses a screw rod (3) and with screw rod (3) complex nut (2), the length of screw rod (3) is greater than the thickness of protective layer, nut (2) upper end is fixed with seals head (1), seal inside cavity of head (1) and inner wall be equipped with with screw rod (3) complex screw thread. The utility model discloses a stainless steel threaded rod and the welding of steel bones RACK, being convenient for, it is perpendicular to guarantee, leaking length outside inspecting after the welding completion, screwing up the nut afterwards, finely tune, the adjustment equals protective layer thickness from the extremely closed first terminal distance in steel bones RACK surface. Install the laggard survey of conducting that finishes, finely tune to the nut that the protective layer is unqualified, have the controllability. Can improve construction progress and engineering quality at double, have good social and economic benefits, have spreading value in the construction of city bridge pier column.