The present disclosure provides an array substrate, a manufacturing method thereof, and a display device. The array substrate includes a substrate, at least one first thin film transistor, and at least one second thin film transistor. A second etching barrier block is disposed between an active layer and a first source electrode, and the first drain electrode is close to the active layer, thereby shortening an effective channel of the first thin film transistor, so that a mobility of transistors and a number of pixels of a panel can be improved.