Abstract: Adopting thermo-gravity settling method to demulsify and dehydrate Liaohe aging oil, the demulsifiers were screened and the effect of demulsification temperature, stirring rate, stirring time, depositing temperature and depositing time on the dehydration of aging oil was investigated. Test results showed that polyether demulsifier could be used for the demulsification/dehydration of Liaohe aging oil with an optimum amount of 400 μg/g. The optimum dehydration process conditions were obtained as follows: demulsification temperature of 80 ℃, stirring rate of 120 r/min, stirring time of 60 min, depositing temperature of 70 ℃ and depositing time of 72 h. When using polyether as main demulsifier and compounded with additive (alcohol/HEDP), treating Liaohe aging oil under the above conditions, the water content of the treated aging oil was 10.8 %, which could be further disposed by electrostatic desalting and dewatering device to reach a water content of less than 0.5%.