A pixel structure, suitable being driven by a scan line and a data line on a substrate, is provided. The pixel structure includes a thin film transistor (TFT) and a pixel electrode. Wherein, the TFT includes a gate, a first and a second dielectric layer, a semiconductor layer, a source, and a drain. Especially, the semiconductor layer has a body part and at least one extending part connected to thereof. The extending part is protruded from the edge of the body part disposed between the source and the drain. In addition, at least one contact hole is disposed in the second dielectric layer for exposing the extending part, and the first dielectric layer, the semiconductor layer, and the second dielectric layer at the extending part are removed through the contact hole. So, leakage current can be effectively reduced, thereby raising the Ion/Ioff ratio of the pixel structure.