A pixel structure includes a substrate, a thin film transistor and a common electrode. The thin film transistor is disposed on the substrate, wherein a semiconductive active layer of the thin film transistor has a channel region disposed between a source and a drain, the channel region includes a main channel region and at least one sub channel region, a channel length of the main channel region is less than a channel length of the at least one sub channel region, and the channel length of the main channel region is equal to a minimum of a channel length of the channel region. The common electrode is disposed on the thin film transistor, and the common electrode overlaps at least a portion of the at least one sub channel region, wherein the common electrode has an opening exposing the main channel region.