Once the pulleys of plastic steel doors and windows need replacing, the doors and windows must be removed; however, the doors and windows are very heavy, especially the double glazing doors and windows, which are located on the outer side of high windows, so it is more difficult to replace the pulleys. According to the plastic steel doors and windows, the frame edge (4) is provided with a drilled axle sheath hole, a pulley (1) is arranged in a groove, and a wheel shaft (3) is arranged in the middle, and the doors and windows can be easily moved. When the pulley (1) needs replacing, as long as the wheel shaft (3) is ejected, the pulley (1) is removed, and a new pulley (1) and the wheel shaft (3) are arranged, the replacement work is completed. When replacing pulleys for traditional plastic steel doors and windows with the pulleys convenient for replacing, first of all, a guide is placed below the frame edge (4), a qualified sheath hole is drilled, and therefore a new pulley (1) and the wheel shaft (3) can be arranged. Because the doors and windows are lifted after the new pulleys are arranged, the old pulley does not need removing.