There are provided a thin film transistor and a manufacturing method thereof, an array substrate, a display device. The manufacturing method includes forming a gate electrode, a gate insulating layer, a metal oxide semiconductor active layer, a source electrode and a drain electrode on a substrate. The forming the metal oxide semiconductor active layer includes forming a zinc oxide-based binary metal oxide pattern layer on a substrate. The pattern layer includes a first pattern, a second pattern and a third pattern. Metal doping ions are implanted into the zinc oxide-based binary metal oxide pattern layer by using an ion implantation technology, so that a binary metal oxide of the third pattern is transformed into a multi-element metal oxide semiconductor, and the metal oxide semiconductor active layer is formed.