A Class C UHF power amplifier is a high efficiency, and high power amplifier operating in ultra-high frequency band (435MHz). The amplifier is a 3-stage cascaded one(Class A-Class C-Class C) with 40dBm(10 watts) power output, 30dB gain, and 55 percent overall efficiency. The first stage(Class A) is designed for high gain, the second and third stages(Class C) are designed for high efficiency. The design rule is the condition of optimum load. The matching networks is designed and implimented using the condition of optimum load. The last 10 watts Class C power amplifier's efficiency is 70 percent.