A structure to increase the breakdown voltage of the high electron mobility transistor is provided to solve the problem of function loss under a high voltage state. The structure includes a substrate, a conducting layer located on the substrate, a gate insulating layer and an electric-field-dispersion layer. The upper portion of the conducting layer is an electron supply layer, and the lower portion of the conducting layer is an electron tunnel layer. The gate insulating layer is laminated on the electron supply layer. The electric-field-dispersion layer is laminated on the gate insulating layer. The dielectric constant of the electric-field-dispersion layer is smaller than that of the gate insulating layer. A gate electrode is located between the electric-field-dispersion layer and the gate insulating layer. A source and a drain electrodes are respectively electrically connected to the electric-field-dispersion layer, the gate insulating layer, the electron supply layer, and the electron tunnel layer.