A microchannel plate is used as a photoelectric conversion component, and a photon counting method is used as a readout method to design a practical fluorescence intensity detector. Combined with the characteristics of the 4B9B photoelectron spectroscopy experimental station of Beijing Synchrotron Radiation Facility (BSRF), a soft X-ray total fluorescence yield absorption spectrum detection system was developed. This detector is equipped with an independent vacuum system to facilitate docking and disassembly of the vacuum chamber of the experimental station, so that the equipment has good portability and convenience. The Ti L-edge absorption spectrum of SrTiO3 crystals with surface-coated ZnS thin films is successfully obtained by using this detection device. Compared with the total electron yield mode absorption spectra, the advantages of the detection equipment for the insulation samples and deep phase detection are demonstrated. The detector has being used in 4B9B photoelectron spectroscopy experimental station, BSRF, which extends the function of soft x-ray absorption spectrum in the study of surface catalysis, electrode materials and thin film substrates and provides a new representation method for the experimental users.