The invention relates to a leg joint rehabilitation device. The problems of single recovery effect and poor effect of an existing joint rehabilitation device are effectively solved. According to the technical scheme for solving the problems, a through groove is formed in a flat plate, a threaded pipe capable of moving up and down and moving left and right is arranged in the through groove, the upper end of the threaded pipe is rotatably connected with a cross rod, a first support plate is hinged to the left side of the cross rod, a sliding plate is arranged on the first support plate, the upper end face of the sliding plate is rotatably connected with a semi-circular arc plate, a foot pedal is hinged to the upper end of the semi-circular arc plate, and a sliding block is hinged to the leftend of the first support plate. A first hydraulic telescopic rod is hinged to the sliding block, the other end of the first hydraulic telescopic rod is hinged to the foot pedal, a second hydraulic telescopic rod communicated with the first hydraulic rod telescopic rod is fixed to the right end of the sliding block, a second support plate is fixed to the right side of the cross rod, a winding wheel is arranged at the front end and the rear end of the cross rod respectively, a rope is arranged on the semi-circular arc plate, and the ropes are respectively wound around the two second winding wheels in opposite winding modes.