Abstract: Nanometer PbS was synthesized by heterogeneous reaction method of hydrogen sulfide gas and lead nitrate solution containing EDTA in ethanol solvent.The influencing factors of product′s particle size were investigated.The structure，mor- phology，particle size，and distribution ranges of the particle size of PbS were characterized by XRD，SEM，and laser sizer re- spectively.Results showed that increasing the initial amount-of-substance ratio of EDTA to Pb（NO3）2，volume ratio of ethanol  to water，and pH，and lowing the flux of H2S gas all will decrease the particle size of PbS.The obtained nanometer PbS had a average particle size of 69 nm，a narrower size distribution，and a spherical shape with cubic crystals when the n（EDTA）/ n［Pb（NO3）2］=1，the volume ratio of ethanol to water was 1，pH=3.5，and the flux of H2S was 20 mL/min.

Key words: nanometer PbS, heterogeneous reaction, complexing agent, ethanol solvent