A sub-pixel unit, an array substrate and a display device are provided. The sub-pixel unit (1) includes a first sub-pixel electrode (10), a second sub-pixel electrode (11) and a common electrode line (12). The common electrode line (12) includes a first common electrode sub-line (120) and a second common electrode sub-line (121); an overlapped area between the first common electrode sub-line (120) and the first sub-pixel electrode (10) is larger than an overlapped area between the second common electrode sub-line (121) and the second sub-pixel electrode (11).