Dual-nut ball screw having preload sensing function achieving better preload sensing sensitivity and effect of force sensor

A dual-nut ball screw having preload sensing function comprises a screw; two nuts; a connecting key; a plurality of balls; a ring-shaped deformable platform, which has a cross section in about a U-shape, and the cross section has a bottom section and two side sections located at two sides of the bottom section and formed with the bottom section as a whole; and a force sensor, which is in a ring shape and disposed at the bottom section of the ring-shaped deformable platform, and located between the two side sections. In which, the bottom section of the ring-shaped deformable platform is extended outwardly with a flange on the other surface opposite to the surface configured with the force sensor. The ring-shaped deformable platform is located in a gap between the two nuts and pressed by the opposite surfaces of the two nuts. In which, on the cross section, the ends of the two side sections are pressed against the opposite surface of one nut, and the surface of the flange is pressed against the opposite surface