A variable-sized screen includes a support, at least one scrolling device and a flexible display. The support has a fixing frame and a movable frame, which are retractably connected. The scrolling device and the flexible display are assembled on the support. The flexible display is wrapped around the support, and the size of the flexible display is variable due to displacement of the support. When the support changes size through a retracted movement of the movable frame and the fixing frame, the flexible display also changes size correspondingly and the size of the screen becomes variable. Therefore, the dimensions of the screen and electronic products are not limited, and the display device has the advantages of a big screen yet is still portable and convenient for a user.