An array substrate and manufacturing method thereof, and a display device are capable of preventing light reflection from a drain electrode, and guaranteeing the display effect of the display device. The array substrate includes a drain electrode of a thin film transistor unit, an insulating layer and a pixel electrode. The insulating layer is located between the drain electrode and the pixel electrode, and has a via hole formed therein, and the drain electrode and the pixel electrode are connected through the via hole. A surface of the pixel electrode at the via hole is a rough face.