The chromatographic behavior of some heavy metals on thin layer of silica gel was studied. The effect of polarity of mixed developing agent systems on the R-f values of metal complexes was investigated. The linear dependence between the R-f values and the polarity of developing agents was deduced and a series of good separations of Cu(II),Co(II) and Ni(II) were obtained successfully. This method was applied to separate Cu(II) and Ni(II) in a real sample.