Abstract: A kind of millimeter-wave transmitter using Traveling-wave Tube(TWT) is introduced in this paper.Its characteristics are presented too,such as broad band,high gain,small size and light weight.This paper describes an approach to design the broad band millimeter-wave transmitter.The structure of high-voltage power supply small size high-voltage rectifier circuit,gated modulator waveform and arc protection circuit are described,and the use of millimeter-wave TWT is described too.Finally,the results of testing and photos are given.