The invention discloses a method for modulating photoluminescence spectrum by infrared light and a device thereof. The device comprises a Fourier transform infrared spectrum measurement system, a laser system as a pumping and detection light source, a phase-locking amplifier and a low pass filter which couple a detector and a circuit control panel in a Fourier transform infrared spectrometer, andtwo choppers which are arranged on an optical path between a test sample and the laser system. The method is characterized by performing measurement of light-modulated photoluminescence spectrum by the device, and being capable of accurately determining energy position of a plurality of optical transitions in photoluminescence signals. The infrared modulated photoluminescence spectrum is a physical differential of the photoluminescence spectrum, and can accurately analyze luminescence process, thus being capable of being used as a reliable and effective means for measuring photoluminescence signals related to a multi-optical transition mechanism. The method and the device have the advantages of rapid and convenient properties, and are applicable to detection of weak luminescence properties of infrared semiconductor photoelectric materials containing impurities and defects.