In order to discuss the regular absorption rules for ammonium with natural zeolite, the authors took the natural clinoptilolite occurred in Zhenjiang, Jiangsu Province as an experimental sample. Its mineral composition and chemical composition were tested. Their adsorption characteristic for ammonium was studied under batch experiment, and its adsorption isothermal lines were established. It is concluded that the adsorption isothermal lines met the formula Langmuir, and its adsorption capacity for ammonium was determined through mathematic analysis.