Abstract: The experimental results of the extraction equlibrium and fractional counter current extraction in system HEH(EHP) -Kerosene-HNO₃-(Sm-Gd)(NO₃)₃ are reported. 96.7% of Sm and more than 99% of Gd were obtained in the raffinate and solvent phase respectively. From the data obtained in the extraction equlibrium a semiempirical distribution model H^a_i3X^a_{j i4}Y^a_i5 (i, j=1,2) has been deduced, which is simple in calculation with a certain accuracy. Non-linear equations for the distribution between aqueous and organic phases and the mass equilibrium in each stage for the counter current. extraction were given. The matrix method and FORTRAN program were introduced for the calculation. The calculated values of metal ion concentration, acidityand concentration of the extractants for each stage are in good agreement with the experimental ones.