Abstract: The mathematical model was studied for the intensification of FCC diesel catalytic oxidation desulfurization by phase transfer catalyst. The mathematical model of diesel desulfurization was established based on the kinetic equations for oxidation reaction of organosulfur compounds, the model equation of intensification for phase transfer catalyst and the equation of sulfides liquidliquid phase equilibrium. It is found that the modeling result of intensification for phase transfer catalyst is precise in the form of exponential function. The model parameters of intensification for phase transfer catalyst, the activation energy and frequency factor of sulfide oxidation reaction, the phase equilibrium constant for solvent extraction are determined through parameter estimation by use of the experimental data of diesel desulfurization. The model prediction shows that the desulfurization degree of FCC diesel changes with the oxidation time. If the oxidation time is short, the desulfurization degree increases with the increase of the amount of phase transfer catalyst. But the desulfurization degree lowers if the oxidation time is longer. The desulfurization degree of FCC diesel increases with increasing the volumetric fraction of oxidation solution or the ratio of extraction solvent to diesel.