In this paper soxhlet extraction method was applied to determine the concentration of volatiles, unsulfonated oil, inorganic salt and pure petroleum sulfonates(PS) in industrial PS, and meanwhile the purified PS was divided into several fractions. The main emphasis is placed on the compositions separation of coarse PS, the effects of the volatiles mass loss time, volume ratio of extractants (n-pentane: isopropanol aqueous solution), gradient solvent types, extracting time× on the separation efficiency of volatiles, unsulfonated oil, inorganic salt and pure PS are discussed respectively. And the extracted unsulfonated oil and the purified PS fractions were characterized by FT-IR spectra and ESI-MS respectively. The experimental results show that after being heated for 3.5h at 130℃, the coarse PS can be permitted to dry, and when the volume ratio of extractants (n-pentane: 50% isopropanol aqueous solution) is 1:3, after several times extraction and anti-extraction, the extracted unsulfonated oil is PS-free, and the pure PS can be successfully divided into four or more extracted fractions with different equivalent weight. Compared with the traditional simply liquid-liquid methods, the proposed method is superior to the traditional ones for simple steps and bifunction with PS purifying&fraction dividing, can separate efficiently industrial PS and other similar mixture.