A power amplifier, comprising: a power dividing unit, a first power amplification tributary, a second power amplification tributary, and an impedance conversion unit, wherein an input end of the first power amplification tributary and an input end of the second power amplification tributary are coupled to two output ends of the power dividing unit respectively, and an output end of the first power amplification tributary is coupled to an output end of the second power amplification tributary through the impedance conversion unit; the impedance conversion unit is configured to perform conversion of output impedance of the first power amplification tributary; the power dividing unit is configured to output a divided power signal to the input end of the first power amplification tributary and the input end of the second power amplification tributary; the first power amplification tributary comprises a main power amplifier, configured to amplify the power signal that is received by the first power amplification tributary and output by the power dividing unit, and output an amplified power signal through the output end of the first power amplification tributary; the second power amplification tributary comprises a peak power amplifier driver, a first inter-stage matching unit, and a peak power amplifier which are sequentially connected in series, wherein the peak power amplifier driver is configured to amplify a received power signal output by the power dividing unit, and then output a power signal amplified by the peak power amplifier driver to the peak power amplifier through the first inter-stage matching unit; the peak power amplifier is configured to amplify a power signal amplified by the peak power amplifier driver and output an amplified power signal through the output end of the second power amplification tributary; the first inter-stage matching unit is configured to match impedance of the peak power amplifier driver with impedance of the peak power amplifier; and rated power of the peak power amplifier driver is less than that of the peak power amplifier; and the rated power of the peak power amplifier is greater than that of the main power amplifier, and the second power amplification tributary is configured to begin amplifying the received power signal when the first power amplification tributary is saturated; wherein a gain of the peak power amplifier driver is greater than that of the main power amplifier driver, and a gain of the peak power amplifier is equal to that of the main power amplifier. a power dividing unit, a first power amplification tributary, a second power amplification tributary, and an impedance conversion unit, wherein an input end of the first power amplification tributary and an input end of the second power amplification tributary are coupled to two output ends of the power dividing unit respectively, and an output end of the first power amplification tributary is coupled to an output end of the second power amplification tributary through the impedance conversion unit; the impedance conversion unit is configured to perform conversion of output impedance of the first power amplification tributary; the power dividing unit is configured to output a divided power signal to the input end of the first power amplification tributary and the input end of the second power amplification tributary; the first power amplification tributary comprises a main power amplifier, configured to amplify the power signal that is received by the first power amplification tributary and output by the power dividing unit, and output an amplified power signal through the output end of the first power amplification tributary; the second power amplification tributary comprises a peak power amplifier driver, a first inter-stage matching unit, and a peak power amplifier which are sequentially connected in series, wherein the peak power amplifier driver is configured to amplify a received power signal output by the power dividing unit, and then output a power signal amplified by the peak power amplifier driver to the peak power amplifier through the first inter-stage matching unit; the peak power amplifier is configured to amplify a power signal amplified by the peak power amplifier driver and output an amplified power signal through the output end of the second power amplification tributary; the first inter-stage matching unit is configured to match impedance of the peak power amplifier driver with impedance of the peak power amplifier; and rated power of the peak power amplifier driver is less than that of the peak power amplifier; and the rated power of the peak power amplifier is greater than that of the main power amplifier, and the second power amplification tributary is configured to begin amplifying the received power signal when the first power amplification tributary is saturated; wherein a gain of the peak power amplifier driver is greater than that of the main power amplifier driver, and a gain of the peak power amplifier is equal to that of the main power amplifier.