Abstract: In view of the traditional class F RF power amplifier caused by parasitic parameters of power amplifier affect LC output second-order impedance matching circuit is not zero and cause of the decline of the efficiency,In this paper, using compensated amplifier tube parasitic parameters and optimizing adjustment of second harmonic impedance method, designed an adjustable structure and stable output circuit unit, then get the higher efficiency and bandwidth; Through the ADS simulation power amplifier working at 1.25 GHz, power added efficiency more than 74.3%, the output power of 47.6 dBm, bandwidth of 240 MHz.