In recent years, with the development of millimeter-wave MMIC chip, millimeter wave technology has been widely used. The millimeter-wave transmitter front-end is designed in this paper. By using second harmonic mixers, we reduce the operating frequency of the oscillator. By using the side exit microstrip - waveguide structure, we strengthen the compact structure. Test results show that the transmitter front-end transmission power is 33dB and its transmission band is 35.5-36GHz.