Shock absorber and vehicle

The invention discloses a shock absorber and a vehicle. The shock absorber comprises a cylinder body, and the cylinder body comprises an outer cylinder sleeve and an inner cylinder sleeve; the piston mechanism comprises a piston rod and a piston arranged on the piston rod, the piston is provided with a first annular piece and a second annular piece, the first annular piece can expand and contract in the radial direction, the second annular piece is provided with a clamping jaw, and the clamping jaw of the second annular piece extends into the first annular piece; when the piston rod stretches the piston to enter the inner cylinder sleeve, oil in the inner cylinder sleeve enters the second annular piece, and the clamping jaws of the second annular piece extrude the inner wall of the first annular piece in the radial direction under the action of oil pressure, so that the first annular piece is expanded in the radial direction till the outer wall of the first annular piece is attached to the inner wall of the i