The nonlinearity of RF power amplifiers when they amplify signals causes distortion，which makes a negative influence on the performance of the communication systems seriously. To improve the third order intermodulation distortion，a new analog predistortion was introduced. This predistortion used the concept of complete matching IMD3 generator and two times fundamental frequency offsetting, which eliminated the fundamental frequency of IMD3 generator and reduced interference of the fundamental frequency to three harmonics. The circuit used the concept of pushing power and dualring structure. It optimized IMD3 of the L frequency range of the GaN amplifier obviously to improve the linearity of amplifier. By using the ADS2009U1 software, in the 950MHz single tone signal testing environment, the experiments show that the PAE of this system reached 52.1%. Furthermore, in the 945 MHz and 955 MHz dual tone signal testing environment, IMD3 gains the improvement of 15 dB. This predistortion realized the optimization of linearity in low efficiency loss.