Oxide thin film transistor, OLED display panel and OLED display device

The utility model provides an oxide thin film transistor and a preparation method thereof, an OLED display panel and an OLED display device. The oxide thin film transistor comprises a substrate; wherein the gate insulating layer is arranged on the substrate; the grid electrode layer is arranged on the grid electrode insulating layer; and the interlayer insulating layer is arranged on the substrateand covers the gate insulating layer and the gate layer, and the interlayer insulating layer is an organic material layer. According to the oxide thin film transistor provided by the utility model, the defects of cavities and the like caused by the disconnection of the ILD layer or poor step coverage in the prior art can be avoided. 本申请提供一种氧化物薄膜晶体管及其制备方法、OLED显示面板、OLED显示装置，该氧化物薄膜晶体管包括：衬底；设置于所述衬底之上的栅极绝缘层；设置于所述栅极绝缘层之上的栅极层；设置于所述衬底之上，且覆盖所述栅极绝缘层和所述栅极层的层间绝缘层，所述层间绝缘层为有机材料层。本申请提供的该氧化物薄膜晶体管，可以避免现有技术中因ILD层断线，或阶梯覆盖性较差而出现空洞等缺陷。