In order to analyze and evaluate the characteristics of the component with good interfacial activity and emulsifying property in petroleum sulfonate of Xinjiang oilfield，the liquid chromatography was adopted to perform the fine components separation. The preparative column was a hydrophobic reversed phase column with diameter of 21 mm and length of 250 mm. Structural composition，interfacial activity and emulsifying property were also completed. The results showed that the petroleum sulfonate sample could be effectively separated into fourteen components with obvious structural differences，among which one component with the most excellent interfacial activity and emulsifying property was distinguished. The average molecular weight and distribution range of this component was 432.5（without Na+）and 390—470，respectively. And molecular weight distributing between 405 and 445 was prominent. The mass percentage of most excellent component in petroleum sulfonate was 20.34%. The performance of petroleum sulfonate sample could be improved through the rigorous screening and control for feedstock and production process.