Based on the RF LDMOS transistor and flange from the independent research, a power amplifier was developed for wireless communication as well as L band and S band radar system with high power and efficiency. On the basis of electric grounding and heat sinking, the input and output internal matching circuits were designed to increase the impedance of the transistor. Using the characteristics of the Doherty power amplifier for the backed off efficiency enhancement and internal matching for the invertion of impedance, a power amplifier with the performance of 398 W, 52% at peaking point and 126 W, 43% at 8 dB backed-off power average point was achieved. The optimized technique enhances the backoff efficiency of Doherty power amplifier, 16% relative increasment to common structure, and improves the radio frequency performance of the wireless communication system further.