The invention relates to a one-way automatic stretching pedicle screw and application thereof. The one-way automatic stretching pedicle screw comprises a screw cap, a compressing gasket and a screw body. The screw body penetrates through the screw cap and is limited and fixed through the compressing gasket. The screw body penetrates through a round runway through hole at the tail end of the screw cap, and a spherical joint of the screw body is matched with a spherical joint socket I of the screw cap; the compressing gasket is clamped in, a spherical joint socket II of the gasket is matched with the spherical joint of the screw body, and two edges of the gasket protrude to be clamped to a groove of the screw cap; a cylindrical joint of a screw head with the screw body is matched with the round runway through hole at the tail end of the screw cap and a horn mouth on a single side to realize single planemovement; the invention also discloses an application of the one-way automatic stretching pedicle screw, mobility between the screw body and the screw cap is determined by opening size of the horn mouth so that design of single-plane screws of different mobility requirements is achieved; various specifications can be provided according to different thread sizes of the screw body, and the pedicle screw is adaptable to different occasions owing to screw bodies with different diameters and lengths.