The present disclosure relates to the field of display technology, and proposes an adjustable frame and a foldable display device. The adjustable frame includes a central shaft part, a rotatable frame part, a movable frame part, and an adjustment mechanism. The rotatable frame part is rotatably connected to the central shaft part. The movable frame part is arranged on a side of the rotatable frame part away from the central shaft part. An end of the adjustment mechanism is connected to the central shaft part, and an opposite end of the adjustment mechanism is connected to the movable frame part. The adjusting mechanism is configured to adjust the spacing between the movable frame part and the rotatable frame part with rotation of the rotatable frame part and the movable frame part. The frame is segmented into a rotatable frame part and a movable frame part, and the adjustment mechanism adjusts the spacing between the movable frame part and the rotatable frame part with rotation of the rotatable frame part and the movable frame part so as to adjust the width of the adjustable frame, thus meeting the needs of