Combined with synchronized monitoring techniques, purification processes for active constituent of alkylbenzene sulfonate have been optimized, and the total alkylbenzene sulfonate, mono-alkylbenzene sulfonate and di-alkylbenzene sulfonate can be obtained with purity over 90%. With the above active constituents as standard substances respectively, the determination of alkylbenzene sulfonate content in the original samples was carried out by high performance liquid chromatograph. The results showed the sample contained mono- and di-alkylbenzene sulfonate simultaneously, and the content of mono-alkylbenzene sulfonate was much higher than that of di-alkylbenzene sulfonate. They had maximum absorption at the wavelength of 224 nm, and the absorption coefficients of total alkylbenzene sulfonate and mono-alkylbenzene sulfonate were similar, higher than that of di-alkylbenzene sulfonate. With total, mono- and di-alkylbenzene sulfonate as standard substances respectively, the limits of quantitation were 5 mg/L, 5 mg/L and 10 mg/L, respectively. The determination result of active constituent was about 3% lower with total alkylbenzene sulfonate as standard substance than that with mono- and di-alkylbenzene sulfonate as standard substances simultaneously, owing to the weaker absorption coefficient of di-alkylbenzene sulfonate.