The particle size distribution of oil-water emulsion is one of important characteristics of emulsion.The various factors on particle size distribution of oil-water emulsion are carried out using MS 2000 Micro laser particle size analyzer,the result showed that the emulsion particles became fining by added the surfactant,but the surfactant concentration has little effects on particle size of emulsions.With the salinity increase,the diameters of emulsion particles increased.The particle size becomes bigger with the addition of polymer.With the increase of polymer concentration,the diameters of emulsion particles increased and the size distribution turned wider.