Preparation has been made for the xylan-based solid acid catalyst was used in the two steps of carbonization and sulfonation． The catalyst was applied to the synthesis of benzoxanthenes． A study was conducted of the effects of the reaction temperature，time and dosage of the catalyst on the transversion． Furthermore，the universality and reusability of xylan-based solid acid catalyst were also investigated． Meanwhile，the xylan-based solid acid catalyst was characterized by scanning electron microscope ( SEM) ，Fourier transform infrared spectra ( FT-IＲ) and elemental analysis ( EA) ． The results showed that the catalyst exhibited high catalytic performance in the synthesis of benzoxanthene and their derivatives with good yields at 90 ℃ for 2 h in the presence of xylan-based solid acid ( 40 mg) ． The catalyst could be reused for several times without significant loss in its catalytic activity，indicating that the catalyst possessed excellent stability and recyclability