Abstract: In order to fulfill the detection requirements of ground-based cloud measurement radars, an 8 mm millimeter-wave high power transmitter is developed. Based on the indicator requirements issued by the radar system and the development level of domestic components, the development plan for the transmitter is determined and the system composition and key technologies adopted in design is introduced. A domestic multi electron beam extended interaction klystron is implemented, resulting in effectively expansion of the instantaneous bandwidth of the transmitter and enhancement of its output peak power. Based on the operational parameters of the klystron, a modularized power modulation scheme is developed, with a floating plate modulator being incorporated to enable rapid reconfiguration of radar working pulse width and repetition frequency. The rising edge and falling edge of the RF output for the solid-state power amplifier is shaped, leading to optimization of the spectral width of the transmitter output. The measured results indicate that all requirements of design indicators are satisfied, at the same time, the transmitter has the characteristics of small size, good heat dissipation, convenient maintenance, high reliability, and strong anti-interference ability.