Abstract: To meet the requirement of high speed OOK wireless communication, a 340 GHz waveguide zero-bias detector was designed, fabricated and measured. Firstly, high frequency electromagnetic software HFSS was adopted to establish the accurate model of the quasi vertical diode (QVD) according to its physical structure, from which impedance of the diode could be extracted with the nonlinear equivalent model of the diode. Then, passive circuits such as waveguide to microstrip transition structure and lowpass filter (LPF) were designed, which also had the function of impedance match. Finally, the designed detector had been fabricated and measured. The measured results show that the detector has a peak responsivity of 2 210 V/W at 334 GHz and a typical responsivity of 1 400 V/W over the frequency range from 315 to 357 GHz,with a typical noise equivalent power of 5 pWHz-0.5. At last, the proposed detector was selected to carrier out the 340 GHz high speed OOK signal demodulation experiment. And results show a bit error rate (BER) below 10-12 at 10 Gb/s and a bit error rate (BER) of 3.1510-7 at data rate up to 15 Gb/s at room temperature, which proves that the detector can well meet the requirement of high data rate OOK communication system.