An array substrate, a manufacturing method thereof and a display device are provided. A display unit is disposed on a first surface of a base substrate, and a driving circuit is disposed on a second surface of the base substrate opposite to the first surface, the driving circuit is electrically connected with the display unit through a signal connection structure in at least one via structure, a longitudinal section of the at least one via hole is a trapezoid, and a length of a bottom edge of the trapezoid at one side of the trapezoid close to the display unit is larger than a length of a bottom edge of the trapezoid at one side of the trapezoid away from the display unit.