A display device and an assembling method thereof are provided. The display device includes a display including an annular body, two flexible screens and a circuit board assembly disposed on the annular body. The two flexible screens are attached on an outer surface of the annular body, and opposite first ends of the two flexible screens are spliced with each other. The circuit board assembly is disposed in a mounting groove provided on the annular body and positioned between second ends of the two flexible screens. The circuit board assembly is electrically connected to both of the two flexible screens, and can drive the two flexible screens to display independently.