In this work, we have performed a detailed investigation on optical properties for CdS/ZnSe spherical core/shell quantum dots surrounded by various dielectric matrices such as PVA, PMMA and SiO2. The wave functions and eigenenergies of confined electrons have been theoretically computed using the effective-mass formalism and the density matrix approach. The linear and third-order nonlinear optical properties have been evaluated for different matrices. Our results demonstrated that the linear, third order nonlinear optical absorption coefficients and refractive index changes are considerably sensitive to the geometrical parameters, the incident optical intensity and the dielectric environment.