The silty clay samples from Xiasha zone, Hangzhou city, are put into the reaction tank, which is specially made to investigate the diffusion characteristics of heavy metal copper ion. The silty clay is compacted, and then the solution with concentration of copper sulfate is 1762mg/L are added into one end of the tank. After laid for a time, several soil samples are cut from different positions in the tank, the adsorption contents of copper ion are tested. Experimental results show that the adsorption contents of copper ion in the silty clay decreases with the increase of the diffusion and movement distance. Besides, the relationship between the adsorption contents of copper ion and the diffusion and movement distance can be formulated as an exponential function.