Based on the analysis of the properties of oily sludge samples, the effect of modification parameters, such as liquid to solid (L/S) ratio, agitation temperature, agitation intensity, agitation time and pH on the modification of oily sludge was investigated with the content of oil remnants in dry sludge as a reference index. Remixing experiments were carried out according to a simplex-lattice design, where Sx4056 was used as the demulsifier, petroleum sulfonate as the surfactant and sodium silicate (Na2SiO3) as the dispersant. The surface modification reagent formulation was optimized by a regression equation on the modified effect and based on the amounts of surface modification reagents. The results show that the content of the oil remaining in dry oily sludge is 0.28% of 10.15% oily sludge, when the reagent concentration rises to 3.5 g/L under the optimum experimental conditions.