A green and effective extraction of oily sludge was completed by a hybrid process with tertiary amines (TA) and protonated tertiary amines (PTA), where PTA is the protonated state of TA. Compared with only TA, the crude oil recovery was improved by 3-5 % by the addition of PTA and less solid remained in the recovered crude oil. Additionally, the wettability improved with the absorption of positively charged ions of PTA on the sludge, and the interaction between heavy alkanes of crude oil and PTA promotes the detachment of crude oil from the sludge surface, enhancing the hydrophilicity of sludge. More importantly, the incomplete recovery of TA exactly takes the role of the PTA in the regenerated mixture, which can reduce the loss of solvent.