Abstract: In this paper, the performance characteristics and advantages of the LDMOS power device are analyzed in detail. Compared with Si power device, it has remarkable advantages such as low-cost, high-gain, high linearity, better thermal stability and high reliability, etc. A P band 300W LDMOS power amplifier was developed with the LDMOS power devices. The performances tests of the amplifiers are carried out, which show that compared with Si power device, the performance of Radar transmitter can be improved with the application of the LDMOS power devices. The superior properties of LDMOS power devices make LDMOS technology a prime candidate for use in transmitters for radar systems.