The invention discloses a thermophotovoltaic power generation system spectral measurement method, which is characterized in that thermophotovoltaic cells are arranged around an isotope heat source anda radiation emitter, photoelectric conversion is carried out by absorbing infrared light waves emitted by the isotope heat source and the radiation emitter, and if a spectral measurement device is designed on the surface of the thermophotovoltaic cell, the spectral utilization efficiency of the thermophotovoltaic cell can be reduced. According to the method disclosed by the invention, photovoltaic cells with various spectra are arranged in the areas with oblique radiation light, weak light intensity and unavailable thermophotovoltaic cell distribution, so that the thermophotovoltaic cell caneffectively utilize the area with the strongest light intensity of the radiation spectrum, and the absorption of the radiation spectrum is not influenced.