The invention relates to a digital predistortion system and method of frequency selectivity harmonic suppression. The digital predistortion system and method of frequency selectivity harmonic suppression are characterized in that a parallel binary channel predistortion unit processing framework is utilized; a main predistortion device is used to suppress in-band distortion of a power amplifier at the center frequency; an auxiliary predistortion device is used to suppress harmonic distortion of the power amplifier at the selected frequency; a predistortion parameter estimation module is used to acquire a predistortion coefficient matrix according to the output signals of the main predistortion device and the auxiliary predistortion device and sampling output of the power amplifier at the center frequency and the selected frequency; and the main predistortion device and the auxiliary predistortion device perform predistortion coefficient adjustment according to the predistortion coefficient matrix. The digital predistortion system and method of frequency selectivity harmonic suppression can only suppress the harmonic interference at the interesting target frequency point, thus being lower in the implementation complexity, compared with a multi-channel predistortion method which suppresses a plurality of harmonic waves at the same time. Besides, the digital predistortion system and method of frequency selectivity harmonic suppression perform weighing synthesis on the optimization target of the main predistortion device and the auxiliary predistortion device to form a single target function, and introduce a particle swarm algorithm, thus accelerating the convergence speed of the algorithm.