The low-energy X-ray absorption spectrometer uses X-ray fluorescence spectroscopy (XRF) technology to excite fluorescence by irradiating X-rays onto the sample. It uses Johansson bent crystals to gather the fluorescence onto the detector, which can detect real-time spectra. At the same time, the bent crystals move linearly to Change the Bragg angle at different positions to obtain the full energy spectrum.