The invention provides an 
oxide thin film transistor, a manufacturing method of the 
oxide thin film transistor, an array substrate and a 
display device, and relates to the technical field of 
liquid crystal display. The manufacturing method of the 
oxide thin film transistor includes the steps that a grid 
electrode, a grid insulating layer and an 
oxide semiconductor thin film are sequentially formed in a substrate; first 
photoresist is formed in an 
active layer area of the 
oxide semiconductor thin film, and a channel area is thicker than a non-channel area; the first 
photoresist of the channel area is reserved; a source drain 
metal thin film is formed on 
active layer patterns, second 
photoresist on the source drain 
metal thin film is reserved, and the edge of the first photoresist of the channel area is covered with the source drain 
metal thin film; source 
electrode patterns and drain 
electrode patterns are obtained. According to the 
oxide thin film transistor, the manufacturing method of the 
oxide thin film transistor, the array substrate and the 
display device, when the initial source electrode patterns and the initial drain electrode patterns are formed, the photoresist is utilized to replace a protective layer to protect an 
active layer, the final source electrode patterns and the final drain electrode patterns are formed through a photoresist stripping technology, and therefore the length of a channel of the 
oxide thin film transistor is shortened.