An optical receiving device includes a conversion module, a signal generation module and a control module. The conversion module performs photoelectric conversion and amplification on an optical signal to generate a photocurrent, the signal generation module provides a gain signal, performs transimpedance and amplification on the photocurrent according to an input signal indicating a preset output voltage swing to generate a voltage signal, and generates a measurement signal indicating an average optical power associated with the optical signal according to the photocurrent, the control module outputs a control signal which is variable to adjust a gain of the conversion module, so that a dynamic range of the conversion module changes as the gain of the conversion module itself changes.