The invention provides a magneto-rheological flexible loading device capable of positioning. The device comprises a cylinder body and two square pistons, wherein the square pistons are in square shapes and are arranged in cylinder body inner cavities formed in a first end and a second end of the cylinder body respectively, and the cylinder body inner cavities are square and matched with the squarepistons; a magneto-rheological body is arranged between the square pistons and the cylinder body inner cavities, and each end part of the cylinder body is provided with an end cover in an attached mode respectively; each square piston is fixedly connected with a piston guide rod, wherein the piston guide rods penetrate through the end covers and are distributed in the axial direction of the cylinder body; and a plurality of magnetic coils are arranged in the middle part of the cylinder body in a wound mode. According to the device, the relative rotation of the pistons in the cylinder body canbe limited, and the positioning function can be realized while the magneto-rheological flexible loading is completed, so that the application of the magneto-rheological device in the loading field isgreatly expanded, and the problem of precise flexible positioning and loading is solved.