The invention provides an array substrate, a manufacturing method thereof and a display device, and aims to solve the problems of complex process, high cost and long consumed time and increase storage capacitance at the same time. Data lines and public electrode lines on the array substrate are separately arranged on a substrate in a same-layer manner and positioned below an active layer, a connecting area is arranged on each public electrode, at least part of the connecting area is overlapped with the corresponding public electrode line in an orthographic projection direction, and the public electrodes and the public electrode lines are electrically connected through first via holes between the connecting areas and the public electrode lines.