Abstract: An ascending/descending guiding structure of a support arm of a display, including a sleeve and a slide member. The sleeve defines a receiving space in which the slide member is slidably received. An inner face of a wall of the receiving space is formed with multiple longitudinally extending channels or ribs. An outer face of the slide member is formed with longitudinally extending ribs or channels in cooperation with the channels or ribs of the receiving space of the sleeve. The ribs are inlaid in the channels and guided by the channels, whereby the slide member can be smoothly stably extended out of the sleeve or retracted into the sleeve at low frictional resistance. The outer face of the sleeve is further formed with outer ribs for abutting against an inner face of the jacket so as to prevent the jacket from abrading and wearing the outer face of the sleeve. The ascending/descending guiding structure further includes a jacket holding the slide member.