The invention discloses an ultra-wideband high-power amplifier. The amplifier comprises an input artificial transmission line matching network, an input absorption load, a high-power low-frequency amplification network, a first medium-power medium-frequency amplification network, a second medium-power medium-frequency amplification network, a high-power high-frequency amplification network, an output artificial transmission line matching network and an output absorption load. According to the invention, the advantages of a single transistor structure amplifier and a distributed amplifier are combined, the ultra-wideband high-power amplifier has the advantages of being high in power output capacity, high in power gain, good in input and output matching characteristics, low in cost and the like under the ultra-wideband condition, meanwhile, the low breakdown voltage characteristic needing to face the integrated circuit technology in the design of the high-power power amplifier is avoided, and the stability and reliability of the circuit are improved.