A flexible display device is provided, which includes a housing, a sliding assembly, and a flexible assembly. The flexible assembly includes a first section and a second section, and the second section is positioned in the housing. When the flexible display device is displayed on a small screen, the first section is in a display state, and the second section is in a non-display state. When the flexible display device is displayed on a large screen, the sliding assembly moves the second section from within the housing to a surface of the sliding assembly, the first section and the second section are in the display states.