Abstract: In this paper we propose an cascaded adaptive predistorter implemented by rational function,applied to linear adaptive power amplifiers in mobile transmitters.Base on polar coordinates representation,the adaptive predistorter of rational function has low complexity in implementation and a fast rate of convergence.The performance of the proposed cascaded adaptive predistorter of rational function is illustrated by linearizing traveling wave tube(TWT) nonlinear amplitude and phase characteristics,suppression of intermodulation products.The result of computer simulation shows that the method converges fast and robust ability of suppression,and so on.