Mesoporous BaO-SBA-15 was directly synthesized in hydrothermal system, and then K2O/BaO-SBA-15 materials were synthesized by impregnating BaO-SBA-15 in different concentration KNO3 aqueous solution. The obtained materials were characterized by XRD, FT-IR, N-2 adsorption/desorption and CO2-TPD. The results indicated that K2O/BaO-SBA-15 was of typical mesoporous structure and the long range order, and the introduction of K species improved the basicity of mesoporous material. The synthesized mesoporous materials were used as catalysts in the degradation of polystyrene (PS) and among them, 9 % K2O/BaO-SBA-15 exhibited the highest catalytic performance. Under the optimum conditions, the conversion of PS was 95.8 wt.% and the yield of styrene monomer could reach 85.0 wt.%. Furthermore, the stability of catalyst was investigated. The results showed that the catalyst was of excellent catalytic stability, there were less decreases in PS conversion and liquid product yield after six successive cycles of the catalyst. [GRAPHICS] .