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 in turn on a substrate patterned by a first multi-tone mask (MTM) to form a gate, a common electrode and a reflecting layer; depositing a gate insulation layer and a semiconductor layer patterned by a second MTM to remain the semiconductor layer on the gate; and depositing a second metal layer patterned by a third MTM to form a source and a drain.