The invention provides a power amplifier system, a control method and a control device thereof. The control device of a power amplifier leads the power amplifier system to be operated in a non-linear switching mode according to the size of a wave packet of the input signals; and when the power amplifier is operated in the non-linear switching mode, the control device provides the supply voltage and the power amplifier input signals to the power amplifier corresponding to input signals according to the characteristics obtained by the pre-measurement power amplifier, to ensure that the power amplifier has high power-added efficiency (PAE) and better degree of linearity.