Abstract: This paper describes an experiment system of Ka-band extended interaction klystron (EIK) transmitter, whose core component is a domestic extended interaction klystron with 35.01 GHz of center frequency, 10 kW of output pulsed power and 0.5% of maximum duty cycle. The experiment system is an advanced research prototype of key component localization of Ka/W band dual frequency millimeter wave cloud-meter transmitter. The performance of the prototype EIK is tested completely, and analysis of potential application problems for EIK are also included in the experiment system. On the other hand, the electrocircuit of transmitter is optimized to meet optimum work requirement of EIK. Experimental results show that enormous progress has been made on domestic Ka-band extended interaction klystron technology and in some areas EIK transmitter has reached the practical stage.