Based on independent electron approximation, we have studied the delayed maxima of photoionization cross section of 4d→f transitions for Xe atomic ions. We illustrate the relations of delayed maxima with the enhancement of corresponding final channel electron collision with the residual atomic ions and relations of secondary delayed maxima with the difference of quantum defects of initial and final states. Our results show: (1) As the degree of ionization increases, the delayed maxima will move towards low energy and finally disappear. (2) for Xe atomic ions, the smaller the absolute value of difference of quantum defects of initial and final states is. the low energy the Cooper minima position is.