An array substrate and a liquid crystal display device adopt a four-domain electrode structure and have advantages of improving the gradient of a V-T curve and contrast, achieving ideal response time, and the like. The array substrate comprises gate lines, data lines and pixel units defined by the gate lines and the data lines. Pixel electrodes (10) and common electrodes (11) arranged on the same layer are formed in the pixel units. Both the common electrodes (11) and the pixel electrodes (10) adopt a comb structure, and comb teeth of the common electrodes (11) and comb teeth of the pixel electrodes (10) are alternately arranged. Each comb tooth of the comb structure is divided into an upper comb tooth (13) and a lower comb tooth (14) in different directions by a node (12). All the upper comb teeth (13) are parallel to each other, and all the lower comb teeth (14) are parallel to each other. For a pixel electrode (10) and a common electrode (11) that are neighboring each other, a spacing (151) between two upper comb teeth (13) is unequal to a spacing (152) between two lower comb teeth (14).