The invention discloses a connection structure of a wing box section test piece, which belongs to the field of aircraft body test design. The connection structure comprises butt corner pieces and a butt strip plate. The butt corner pieces are arranged at the joint of the wall plate of the body and a dummy wall plate. Each butt corner piece is L-shaped. Two butt corner pieces clamp the body wall plate and the dummy wall plate on both sides. The butt strip plate is arranged on one side, which is away from the butt corner piece, of the body wall plate. The butt strip plate abuts against the bodywall plate and the dummy wall plate. Two butt corner pieces are separated and do not need to be inserted and aligned, which reduces the requirement for the axis degree, simplifies assembly positioningand improves the assembly efficiency. The butt corner pieces are L-shaped. Two adjacent butt corner pieces form a double-shear structure with the body wall plate and the dummy wall plate, which areclamped thereby, to ensure the strength and stability of the butt structure and make the force uniform The butt strip plate abuts against the body wall plate and the dummy wall plate, which increasesthe contact area, and makes the connection between the body wall plate and the dummy wall plate more stable.