Solid adsorption cooling tube driven by waste heat is a novel subminiaturized refrigeration component. Experimental study is carried out for cycle characteristics of an adsorption cooling tube with zeolite-water as a working pair under various refrigerant charge conditions. The cooling tube is a metal tube 16 mm in diameter and 1 000 mm long containing the generator and the condenser/evaporator. The results show that refrigerant will condense or evaporate under the variational saturation pressure and its corresponding temperature almost all along, when the optimum refrigerant is charged in the cooling tube. And the cooling tube will go on with occurrence of the non-saturation process, when the overmuch or deficient refrigerant is charged in it. The research results provide a great help for knowing well the working characteristics of the cooling tube and improving its performance.