The adsorption performance of CaCl2-NH3 is studied under the condition of different expansion spaces for adsorbent, and the relationships between adsorption performance of CaCl2-NH3 and the phenomena of swelling and agglomeration during adsorption are researched. It is found that the performance stability is related to the ratio of expansion space to the volume of adsorbent ras, and the performance attenuation is serious in the case of large ras. Severe adsorption hysteresis exists in the process of adsorption and desorption at the same evaporating and condensing temperatures, which is related to the stability constant of chemical reaction. This phenomenon cannot be explained by the theory of physical adsorption. Moderate agglomeration will be beneficial to the formation of ammoniate complex; the magnitude of expansion space will affect adsorption performance. Analysis shows that the activated energy needed in the process of adsorption for the sample with ras of 2:1 is less than that for the sample with ras of 3:1. The refrigeration performance of CaCl2-NH3 is predicted from experiments. The cooling capacity of one adsorption cycle is about 945.4kJ/kg for the adsorbent with an ras of 2:1 at the evaporating temperature of 0℃.