Millimeter-wave Traveling Wave Tubes(TWTs) have the characteristics of high power, broad band and high gain, and are widely used in modern military electronic equipment, such as radar, high-speed communication and electronic countermeasures, etc. In order to improve the coupling impedance of the Folded Waveguide(FWG) and the engineering applicability, a novel type of ear-FWG is proposed, which increases the coupling impedance in the working frequency band by more than 30% and reduces the loss by 10% compared with the conventional rectangular waveguide. When the ear-FWG W-band TWT operates at 21.9 kV and 210 mA, and the duty cycle is 5%, the output power in the 10.8 GHz bandwidth is higher than 192 W, the peak power reaches 278 W, the electron efficiency and gain reach 6.3% and 44.6 dB, respectively, and the TWT works stably.