A thin film transistor comprises a transparent substrate, a gate is disposed on the transparent substrate, a gate insulator is disposed on the gate and the transparent substrate, an active layer is disposed on the gate insulator, an electrode layer is electrically connected the active layer and the portion of the active layer is exposed, and an ultraviolet light absorbing layer is disposed on the electrode layer. By using the advantage of the ultraviolet light absorbing layer with the range of visible light transmittance and with the component protection, preventing the optical characteristics of the thin film transistor from the outside moisture is achieved, and by adjusting the parameters in the thin film deposition process to change its conductivity.