Abstract: At present, China’s Q/V band low orbit satellite internet project is being vigorously carried out, broadband communications are gradually developing. But the domestic linearization technology is generally limited to narrow band, the related research is not mature. Therefore, it is necessary to design broadband linearizer as soon as possible. In this paper, a Q-band linearizer of traveling-wave tube amplifier (TWTA) for satellite communication has been designed using an analog predistortion technique suitable for space environment. Using the new microstrip transmission structure and the Schottky diode, the ultra-wide instantaneous frequency band can be linearized in the millimeter-wave frequency band. The amplitude distortion and phase distortion of TWTA are greatly improved in the 38−43 GHz (5 GHz) instantaneous frequency band. The linearizer has an in-band amplitude gain of about 4.8−7.2 dB and a phase expansion of about 70°−88° in the input power range of −17−13 dBm. Compared with other linearizers of the same type, this linearizer has higher corresponding frequency and can realize stable linearization of TWTA in a wide instantaneous frequency band.