The energy band and defect energy level state are important parameters in the manufacturing process of narrow band gap semiconductor material chips. Infrared modulated photoluminescence(PL)spectrometer is a non-destructive and effective detection technology. This technology is used to detect different narrow band gap semiconductor materials. The spectral results are fitted with a line type to reveal the electronic transitions between different energy levels, and the results are analyzed. The results show that infrared modulated PL spectroscopy is an effective method for studying energy bands and defect energy levels of materials.