A method of forming TFT is provided. The TFT includes a gate electrode, a gate insulating layer, a first protective pattern, a second protective pattern, a source electrode, a drain electrode, a semiconductor channel layer, and a passivation layer. The first protective pattern and the second protective pattern are disposed on the gate insulating layer above the gate electrode. The source electrode is disposed on the gate insulating layer and the first protective pattern. The drain electrode is disposed on the gate insulating layer and the second protective pattern. The semiconductor channel layer is disposed on the gate insulating layer, the source electrode, and the drain electrode. In an extending direction from the source electrode to the drain electrode, a length of the first protective pattern is shorter than that of the source electrode, and a length of the second protective pattern is shorter than that of the drain electrode.