Petroleum sulfonate (PS) surfactant used for enhanced oil recovery was synthesized by dilute liquid sulfur trioxide and petroleum fraction (PF) of Shengli crude oil as raw materials with the application of HIGEE process intensification technology. The effects of various experimental conditions on the content of active matter and unsulfonated oil were investigated. The optimum conditions were selected as solvent/oil mass ratio 0.5, SO3/oil mass ratio 0.525, reaction temperature 30 degrees C, rotating speed 1200 rpm, circulation ratio 4, reaction time 15 min and aging time 50 mm under which the active matter content was up to 45.3 wt.% and the oil/water interfacial tension was as low as 4.5 x 10(-3) mN/m. The higher product quality and higher process efficiency of this new technology is proven by a comparison with traditional STR process. (C) 2010 Elsevier B.V. All rights reserved.