A new chemiluminescence (CL) method using water-soluble mercaptoacetic acid (MAA) capped CdSe quantum dots (QDs) as sensitizers is proposed for the determination of Pb2+. MAA-CdSe QDs were synthesized by using MAA as stabilizerin aqueous solutions. The stability of QDs were studied. The shape, size and spectral properties Of MAA-capped-CdSe QDs were characterized by Ultra Violet-Visible absorption Spectroscopy, transmission electron microscopy (TEM) and spectrofluorometry. A pH 6 was selected for measurement. Also the influence of the foreign cations, drugs and amino acids on the fluorescence intensity of MAA-CdSe QDs was studied and Results showed a high selectivity of the MAA-CdSe QDs towards pb2+ ions. There is a good linear relationship between the relative chemiluminescence intensity and the concentration of pb2+ in the range of 1.6×10-9-1.3×10-8M of pb2+ ions with a correlation coefficient (R2) of 0.9967. The limit of detection of this system was found to be 1.1×10−9 M. This method is simple, sensitive and lowcost.