The invention provides a hidden myopia-prevention rack with adjustable height, and relates to the technical field of devices arranged on a desk. The upper part of an upright post (5) is provided with a rotating shaft punch hole (21). A U-shaped clip (3) is fixed on a body-blocking plate seat (2), on which a body-blocking plate (1) is arranged. The lower part of the upright post is provided with an upright post drop-proof screw (9). The upright post is inserted into an upright post adjusting port (22) of an upright port retraction seat (7). A retraction seat lug of the upright port retraction seat is connected in series between two serial screw passing openings of a retraction rod by a serial screw (8). The end part of the retraction rod is provided with upright post clamp apparatuses (17). Rubber caps (6) are sleeved on two upright post clamp apparatuses respectively. The retraction rod is arranged in a retraction rod opening of a retraction rod clamping seat (12) arranged at one end of a fixing plate (10). The two sides of the fixing plates are provided with thickened edges respectively; and the other side of the fixing plate (10) is provided with a fixing hole (14) connected and fixed with the back part of a desk surface.