Millimeter-wave systems have been widely applied in military communications. As a key component, the output power of millimeter-wave transmitter has become an important parameter to evaluate these systems’ performance. This study designed a Ka-band solid-state power amplifier, and analyzed the problems of circuit stability about debugging. The measurement result indicated that the gain was more than 35 dB within f0±1.5 GHz, and P-1 was 33 dBm.