The invention relates to the technical field of manufacture of displays, in particular to a medium-free tripolar field emission display (FED) device having single-cathode and single-gate type transmission units and a driving method for the device. The device comprises an anode plate and a cathode gate plate which are arranged in parallel. The device is characterized in that: cathodes and gates are distributed uniformly on the cathode gate plate at intervals; the cathodes and the gates are arranged cyclically on the cathode gate plate according to a cathode-gate structure to form a plurality of electronic transmission units which are arranged in parallel sequentially and have the cathode-gate structure on the cathode gate plate; each cathode and each gate are in a vacuum state; and anodes are distributed uniformly on the anode plate at intervals correspondingly. In the driving method, a cathode-gate voltage is used for scanning, and an anode voltage is used for signal regulation; when each electrode of the cathode gate plate serves as the cathode or the gate fixedly, a fixed voltage is adopted for driving; and when the electrodes on the cathode gate plate can be interchanged in a cathode-gate mode, a pulse scanning driving method is adopted. The device is simple in manufacturing process and low in manufacturing difficulty. The corresponding driving method is convenient for improving the working performance of the FED device.