The main difficult problem was decolorization in the treatment of dye wastewater. Organic modified montmorillonite could be a good adsorbent to settle this problem. An organic modified montmorillonite was prepared using microwave irradiation method instead of common water bath heating method, and the decolorization on dye watewater of acid fuchsin was reasearched. Its decolorization on acid fuchsin solution was better obviously than that of montmorillonite. And the decolorization rate was increase with the increase of the initial concentration of acid fuchsin. When the concentration of acid fuchsin solution was 40 mg/L, the optimum decolorization condition was 0.1 g of adsorbent quantity, 6.1 of pH, 30 min of contact time, and 25 °C of operation temperature.