A manufacturing method of an array substrate is disclosed. The manufacturing method includes a step of forming a pattern including a pixel electrode; and the manufacturing method further includes a step of forming a pattern including an active layer after the step of forming the pattern including the pixel electrode. Accordingly, an array substrate and a display device are also disclosed. In the manufacturing process of the array substrate, conductive material remained on the active layer is less, thereby producing less leak current, which in turn improves quality of the array substrate and display performance of the display device.