Abstract: Aim at radio frequency nonlinear behavior modeling technology, this paper proposes a new load-independent X-parameters extraction method of transistor model, and designs power amplifier using this transistor model. The method combines the traditional X-parameter extraction with load-pull technology, and then uses iteration to obtain load-independent transistor X-parameters model and the optimum load impedance. Comparing with load-dependent X-parameter model, this model is more applicable to circuit analysis and design. It has small data volume and the steps are simple with short time.The model is applied to broadband power amplifier design, using Chebyshev low-pass impedance transformation, matching network is designed. Measured results and simulation results show that: across the frequency band, both output powers are more than 4W with 14dB power gain and 45% PAE. So the X-parameter extraction method is proved to be correct.