The present invention discloses a thin-film transistor (TFT) array substrate and a manufacturing method thereof. Depositing a transparent conductive layer and a first metal layer on a substrate, which is patterned by a multi-tone mask (MTM) to form a gate, a common electrode and a reflecting layer; depositing a gate insulation layer, which is patterned by a first mask to remain the gate insulation layer on the gate; depositing a semiconductor layer, which is patterned by a second mask to remain the semiconductor layer on the gate; and depositing a second metal layer, which is patterned by a third mask to form a source and a drain.