The investigation and development of novel functional organic material for the adsorption of heavy metal ion in water is one of the important solutions to water pollution. However, with traditional techniques, it is very difficult to observe directly the distribution of heavy metal ion inside the adsorptive material. By means of the tunability and penetrability of the X-rays, this problem is researched with K-edge digital subtraction (KES) imaging. Systematical investigation is carried out successfully, resorting to optimization for experimental conditions, image registration and median filtering etc.. The experimental results demonstrate that the adsorbed copper ions can infiltrate into the adsorber. The results also indicate that sizes of the adsorbing particles do not have obvious impact on the infiltrating depth of the copper ions. The mass of the copper ions adsorbed per unit time is mainly affected by the superficial area.