Abstract: Behavior of floation of merury(Ⅱ) from aqueous solution of NH4SCN and CPB in the presence of NaCl and the condition of separation of mercury(Ⅱ) from commonly encountered ions were studied.As shown by experimental results,mercury was separated quantitatively by floation from aqueous solution containing 0.5 mL of 0.1 mol·L-1 NH4SCN solution and 1.0 mL of 1.0×10-2mol·L-1 CPB solution in a total volume of 10 mL including 5 mL of buffer solution to control the acidity at pH 5.0.One gram of solid NaCl was added to the solution.Cadmium(Ⅱ),Ni(Ⅱ),Co(Ⅱ),Mn(Ⅱ),Fe(Ⅱ) and Al(Ⅲ) did not undergo floatation and were separated from mercury(Ⅱ) under the condition described above.Test for the recovery of mercury from simulated water samples containing the aboved mentimed ions and 50.0,100.0,200.0 and 400.0 μg of Hg(Ⅱ) separately,value of average recovery of Hg(Ⅱ) was found to be 100.5%.