To find appropriate humidity-controlling material, the authors studied sepiolite and its compound samples for the capacity of moisture absorption and desorption. The relative humidity of a 10 liter glass vessel could be reduced from 70% to 4% by 10g sepiolite, whose moisture adsorption capacity isstronger than that of palygorskite under the same condition. The moisture adsorption capacity of sepiolite (10g) will somewhat weaken after three circulations of absorbing and desorbing experiments. In the last experiment, the sepiolite (10g) absorbed about 0.4g moisture and released some 0.15g moisture. It has been found that 30g sample of sepiolite compounded with white cement can keep the humidity in the range of 40%～50% in a 10 liter glass vessel. Sepiolite can be used as building materials for indoor air humidity control.