A power amplification device, including a first amplification branch, a second amplification branch, a harmonic injection circuit, and a first output matching circuit. A first amplifier in the first amplification branch supports a first frequency. A second amplifier in the second amplification branch supports the first frequency and a second frequency, and the second amplifier is turned off for a signal of the first frequency that has a power value lower than an enabling threshold. The harmonic injection circuit injects a signal of the second frequency that is input from a second input terminal (I2) to a signal of the first frequency that is input from a first input terminal (I1) to obtain a signal of the first frequency that has undergone harmonic injection.