A new approach to extract reliable intensities from systematical non-equivalent overlapping reflections has been proposed and tested by simulated powder diffraction pattern of known structures. By using both crystallographic and structural chemistry knowledge, the IDM-UAIC reconstructs the intensities and solves the structure through an iterative procedure. The results show that IDM-UAIC succeeds when more than 30% of the total scattering power can be located in a reasonable precise from the equivalent systematical overlapping reflections. The IDM-UAIC procedure is superior to the simple equi-partition methods for the nonequivalent systematical overlapping reflections while it is equivalent to simple equi-partition methods for the equivalent systematical overlapping reflections.