The invention provides a multifunctional root rib for the all-movable rudder surface model of a supersonic wind tunnel. The multifunctional root rib comprises a root rib body and reinforcing ribs. Each of the reinforcing ribs is of an arc-shaped structure which protrudes upwards. The reinforcing ribs are perpendicularly fixed to the upper end surface of the root rib body. Beam frame positioning clamp pieces are distributed on the upper end surface of the root rib body and the outer surfaces of the reinforcing ribs. An adapter used for being connected with a decoupling pin and a flange bolt fixing hole are arranged on the lower surface of the root rib body. The adapter is enabled to be perpendicular to the root rib body. The multifunctional root rib is simple in structure. The arc-shaped reinforcing ribs are arranged on the root rib body, so that the strength of the root part of a wing can be increased to the maximum degree. The beam frame positioning clamp pieces are arranged on the root rib body and the reinforcing ribs, and are used for fixing the beam frame of the wing. Therefore, the root rib body is fixedly connected with the beam frame of the wing. The bending moment and theshearing force on the beam frame of the wing are guaranteed to be transmitted to the root rib body to the maximum degree. The safety and reliability problem of the all-movable rudder surface model issolved, and the connection of the model with an external measuring device is facilitated.