The invention discloses a pixel unit structure, an array substrate and a display device and relates to the technical field of liquid crystal displays. The pixel unit structure has a storage capacitor and has a high aperture ratio and a low manufacturing cost of the pixel unit. The pixel unit structure comprises a thin film transistor (TFT) and a first barrier layer, wherein the first barrier layer is opposite to a drain region of an active layer of the TFT, and is connected to a common electrode of an array substrate, thereby a capacitor can be formed between the first barrier layer and the drain region of the active layer.