A display device including a thin film transistor array substrate, transparent electrode substrate and a display medium layer disposed therebetween is provided. The thin film transistor array substrate includes a plurality of thin film transistors with an oxide semiconductor layer respectively. In each thin film transistor, a gate electrode and a gate insulating layer are disposed on a substrate sequentially and the gate electrode is covered by the gate insulating layer. The oxide semiconductor layer is conformably covering on the gate insulating layer and has a channel region located above the gate electrode. A source electrode and a drain electrode of each thin film transistor are disposed on the oxide semiconductor layer and at one side of the channel region respectively. Since the oxide semiconductor layer is made of transparent material, the patterning process of the oxide semiconductor layer can be omitted during the manufacturing process of the reflective display device. Thus, the cost and time-consumed of manufacturing process of the reflective display device can be reduced.