In recent years, with the wide application of photovoltaic detectors in the field of Fourier transform infrared spectroscopy (FTIR) detection, the nonlinear response of photovoltaic devices has increasingly become a key issue affecting the accuracy of FTIR spectroscopy inversion. Firstly, the general principle and equivalent circuit of the photovoltaic detector were summarized. Then, the internal effects and external factors leading to the nonlinear response of the detector were analyzed. Finally, the correlation between the internal and external factors was summarized, and the working direction of nonlinear correction of the detector was given in the conclusion. The nonlinear response of photovoltaic detectors was investigated in this paper. This is important for revealing the response law of semiconductor devices to different fluxes of radiation, for improving the study of nonlinearities in photovoltaic detectors, and for improving the accuracy of FTIR detection.