A method for manufacturing an organic light-emitting diode (OLED) backplane is provided. The method includes sequentially depositing a first oxide semiconductor layer, a second oxide semiconductor layer and a third oxide semiconductor layer to obtain an active layer of a thin film transistor. The flow ratio of an argon gas and an oxygen gas introduced during the deposition of the first and third oxide semiconductor layers is greater than the flow ratio of the argon gas and the oxygen gas introduced during the deposition of the second oxide semiconductor layer. As a result, the oxygen content of the first and third oxide semiconductor layers is greater than the oxygen content of the second oxide semiconductor layer. Therefore, the conductivity of the active layer of the thin film transistor device is enhanced. The interface defects are reduced. The stability of the thin film transistor device is improved.