A method and apparatus for signal processing by light waveform shaping are provided to process an uplink signal generated by a digital-to-analog converter (DAC) and/or process a downlink signal to be transmitted to an analog-to-digital converter (ADC). The method includes adjusting the waveform of the uplink signal and/or the waveform of the downlink signal with a light waveform shaping module so that, even if the DAC and/or ADC has a low sampling rate and a narrow bandwidth, a high-frequency signal portion of the uplink signal and/or a high-frequency signal portion of the downlink signal can be preserved.