Abstract: The study on the interrelation between the structures of petroleum sulfonates and interfacial activity, interfacial tension determination and mass spectrum analysis of twenty-five petroleum sulfonate samples from different sources or batches have been carried out. The experimental results showed that the amount of sulfonates with longer carbon chain such as C₁₇~C₂₅ plays a dominant role, the higher content of these components, the better interfacial activity of samples. When the sample molecular weight distributes evenly between 200~800, and when the molecular ion peaks with greatest abundance assemble at 479 or nearby the samples display better interfacial activity.