In this paper, the structured parameters effect on nonlinear optical properties of CdS/ZnS quantum dot (QD)is studied. The self-consistently solved Schrodinger–Poisson equations obtains the QDs energy eigen values and functions. Then, size effect of QDs on energy levels of the ground and first excited states, matrix element and third-order nonlinear susceptibilities related to intersubband transitions are investigated using the density matrix method. The proposed structure results the large dipole transition and high nonlinear and tunable susceptibilities that are very suitable for implementation of active and passive devices and systems. It has been observed that the structure parameters QDs can manage the amplitude and resonance frequency of the nonlinear third-order susceptibilities.