Crystalline dimethylol urea was synthesized, characterized, and used to react with n-dodecyl mercaptan and cotton cellulose in the presence of alkaline catalyst. The hydrolysis rate of dimethylol urea, the reactivity of dimethylol urea with n-dodecyl mercaptan, and the physical and chemical properties of dimethylol urea finished cotton fabrics in the presence of alkaline catalyst were investigated.