In order to obtain the optical coefficient of quantum dots doped glasses and pro vide qualitative and quantitative analysis in the preparation process of quantum d ots,a procedure combining the G.Mie scatter theory and the Kramers-Krnig relations is used to calculate the rea l and imagi nary parts of the dielectric function from the experimental absorption spectrum by iterative method.A simple and quic k method is developed to avoid the singular matrix in the process of matrix iterative approach.The calcu lated results of the dielectric function of PbSe quantum dots doped glasses are very similar to the experimental results of colloidal PbSe quantum dots.This method can conveniently get the dielectric coefficients of many types of materials,such as liquid,solid and gas materials.It can be a good reference for the manufacture of other nano m aterials.