An active device of a pixel structure includes a semiconductor layer, an insulation layer covering the semiconductor layer, a gate electrode disposed on the insulation layer and electrically connected to a scan line, a protection layer covering the gate electrode, a source electrode and a drain electrode electrically connected to a source region and a drain region of the semiconductor layer. A channel region is disposed between the source region and the drain region. A source lightly doped region is disposed between the channel region and the source region. A drain lightly doped region is disposed between the channel region and the drain region. The light shielding pattern shields the source region, the drain region, the source lightly doped region and the drain lightly doped region. The light shielding pattern is overlapped with one side of the scan line and not overlapped with another side of the scan line.