The exciton energy levels and wave functions of (nc-Si/SiO2)/SiO2 multi-layer structure are analyzed, by using the spherical quantum dots model and effective mass approximation theory. The model of finitely deep potential well makes the resuct more accurate and near to reality. The conclusion shows that the ground. State energy of mass center′s motional part increases rapidly as the radius of quantum dot decreases, no matter in infinitely deep potential well or finitely deep potential well. The mass center energy in infinitely deep potential well is always higher than the finitely deep potential wells with same radius of quantum dot, and their differences increase as the radius of quantum dot decreases.