Provided is a dual-mode power amplifier with switchable operating frequencies, comprising at least two preamplifier circuits, a matching circuit for matching an output signal of each preamplifier circuit, an input transformer T1 with at least two output taps, an output stage amplifier circuit with the same number as the output taps of the input transformer T1, an output transformer T2, a switch S1 and a switch S2; circuit power supply VCC1 is loaded on an input end of the input transformer T1 via switch S1 and switch S2 respectively; operating frequencies of the matching circuit are different. The power amplifier realizes the switching of the maximum output power, supports the signal amplification in more frequency bands, and solves the problems in the prior art that the number of components is too large because more groups of power amplifiers for power amplification are needed for different frequency bands.