The invention discloses a novel high-performance light modulation thin film transistor based on a quantum dot doped gate insulating layer. A preparation method thereof comprises the following steps: depositing an active layer and a source and drain electrode contact layer on a base in sequence; spinning quantum dots and organic optical cement on the active layer to prepare the gate insulating layer; etching via holes for connecting the contact layer with active and drain electrodes on the gate insulating layer; and finally preparing a transparent electrode on the gate insulating layer, and etching the transparent electrode as the drain electrode, gate electrode and source electrode of a plane. Besides the three modulation electrodes of a traditional source and drain gate, the thin film transistor device disclosed by the invention can be taken as a fourth end modulation electrode through incident light. The light modulation thin film transistor with photoelectric detection and signal read functions is prepared by using the thin film transistor gate insulating layer doped with the quantum dots, so that the structure and preparation technology of the light modulation thin film transistor are greatly simplified, the dimensions of the device are shortened, and the photoelectric detection performance is improved.