The invention provides an array substrate, a manufacturing method of the array substrate and a display device. The manufacturing method includes the steps that photoresist is coated to an insulating layer covering a conductive pattern or a semiconductor pattern; exposing is carried out to at least form a photoresist partial reserving area and a photoresist complete removing area; etching is carried out to at least partially remove the portion, corresponding to the photoresist complete removing area, of the insulating layer so as to form a middle hole; etching is carried out again to form a first via hole, a second via hole is formed in the position of the middle hole, and the portions, where the first via hole and the second via hole are formed, of the conductive pattern or the semiconductor pattern are exposed, wherein the depth of the first via hole is smaller than the depth of the second via hole. By means of the array substrate, the manufacturing method of the array substrate and the display device, on the premise that the number of times of composition processes of the array substrate is not increased, the condition that when a shallow hole and a deep hole are etched at the same time, an oxide semiconductor layer and a gate insulating layer at the position of the shallow hole are punctured through etching due to long-time etching, so that a single line and a gate line are in short circuit is avoided.