Sulfur metal-organic complex Pb(S2CNEt2)2 is synthesized with Pb(NO3)2 and Na(S2CNEt2)·3H2O as reactants in deionized water. Under the protection of argon, PbS quantum dots are synthesized by pyrolysis of the precursor Pb(S2CNEt2)2 in oleic and octadecene mixed solution. Four samples a, b, c, and d of PbS quantum dots are synthesized on the condition that the reaction times are 30, 60, 90, and120 min, respectively. Infrared spectrum of the precursor Pb(S2CNEt2)2 shows that two sulfur atoms of the ligand Na(S2CNEt2)·3H2O have successfully coordinated with Pb2+. X-ray powder diffraction and transmission electron microscopy results show that the PbS nano crystals are of pure cubic phase structure, and are well-dispersed spherical particles. UV-visible absorption spectrum and photoluminescence spectra of PbS quantum dots show that absorption spectrum and photoluminescence spectra both have red-shift along with reaction time extending. This indicates that absorption spectrum and photoluminescence spectra can be modulated by optimizing the thermal decomposition reaction time. The emission peak of sample is located at 1080 nm, which is matched to the silicon solar cell. It can be used as the fluorescent material of silicon luminescent solar concentrator.