Provided by an embodiment of the present invention are a power amplifier protection method and device, the device comprising: a baseband signal receiving module, which converts a received optical signal into a baseband digital signal; a baseband power amplifier protection module, which detects whether the power of the baseband digital signal is greater than a power threshold of a linear region of a power amplifier and which adjusts the power of the baseband digital signal to be within the power threshold of the linear region when the power of the baseband digital signal is greater than the power threshold of the linear region; a digital-to-analog converter (DAC) front power amplifier protection module, which detects whether the power of a power amplifier input signal that has been processed by means of a signal processing module of a power amplifier front end is greater than the power threshold of the linear region and which adjusts the power of the power amplifier input signal to be within the power threshold of the linear region when the power of the power amplifier input signal is greater than the power threshold of the linear region; a digital-to-analog conversion module, which converts a processed digital signal into an analog signal and which sends the same to the power amplifier. The present invention may effectively control signal power so as to achieve a protective effect for a power amplifier and increase the reliability of the system.