This article used bentonite impregnated with titanium and silver, respectively, as photocatalyst, to degrade methylene blue (MB) under conditions of MB solutions exposed to sodium lamp and sunlight. Due to the semi-conducting properties of synthesized bentonite catalysts, when exposed to sodium lamp and sunlight, catalyst particles are excited for photocatalysis to achieve decolourization. After an FT-IR analysis, this study finds that smectite catalysts have significant and complicated wave crests between the fingerprint area with wave numbers 415~600 cm⁻¹ and 750~1170 cm⁻¹. The bentonite impregnated with Ti(4+) (Sm-Ti) and with Ag⁺ (Sm-Ag) removes MB through the mechanisms of adsorption and degradation, while the commercial product of titanium dioxide (TiO₂) only exhibits the capability of MB degradation. At present, a heterogeneous photocatalytic system has been fully applied for use in daily life, with its efficiency determined by the free radical action of electrons and holes, the generation efficiency of ·OH.