A thin film transistor array substrate, a manufacturing method thereof and a display device are provided, and the thin film transistor array substrate includes: a base substrate, a gate electrode disposed on the base substrate, a gate insulating layer and an active layer which are disposed on the gate electrode sequentially, and a pixel electrode, a common electrode, and a transparent electrode layer which are disposed on the base substrate; the transparent electrode layer and the pixel electrode or the common electrode are prepared in a same layer and by a same material; the transparent electrode layer is disposed under the gate insulating layer; an orthogonal projection of the active layer on the base substrate is located within a region of an orthogonal projection of the transparent electrode layer.