Water-assisted solvent extraction method was used to recovery qualified oil from oily sludge. Based on the solubility parameter and“rule of similarity”，several efficient solvents were selected. Through the mixture of solvent to adjust the solubility parameter researchers developed a highly efficient，harmfulless and environmental friendly extracting solvent. The extracting solvent consisted of hexane（A2），mixed naphthenes（A3）and alcohol ether mixture（B1）. The volume ratio of A2∶A3∶B1 was 0.5∶0.3∶0.2. The influence of ratio of solvent to mud，extracting temperature，extracting time and stirring rate on the effect of extraction was studied. The results showed that the optimum extraction condition was obtained as follows：5∶1 ratio of solvent to mud，35℃ extraction temperature，45 min extraction time，160 r/min stirring speed. The residual oil rate of crude oil was 3.65% under the optimum extraction condition. The extracting solvent had good oil removing rate，the interface of oil and water became very obvious without emulsification and the water could separate from oil easily. The crude oil fractions over 350℃ accounted for 74%，which indicated that crude oil was heavier. The content of saturates，aromatics，resins，asphaltenes，S and Ni was 7.54%， 45.13%，28.12%，5.23%，1.99% and 622 μg/g. The water content of oil extracted was 0.8% and reached the requirements of oil transportation.