Abstract: To address the challenges in treating chemical flooding produced liquid in Shengli Offshore Oilfield, this study aims to develop a new and efficient demulsifier. A multi-branched fluorinated polyether demulsifier (MF series) was synthesized using p-trifluoromethylphenol and tetraethylenepentamine as initiators to synthesize a polyether through block polymerization, followed by cross-linking modification with 2,4-toluene diisocyanate (TDI). The demulsifier was characterized by infrared spectroscopy, and its cloud point and hydrophile-lipophile balance (HLB) value were determined. The demulsification performance was evaluated through bottle tests on chemical flooding produced liquid from Shengli Offshore Oilfield, followed by field application on an offshore platform. The results show that the MF-4 demulsifier achieved a demulsification rate of 93.8% within 30 minutes at 60 ℃ with a dosage of 60 mg/L. In field trials, the water content at the oil outlet of the three-phase separator decreased to 29.3% with a residence time of 25 minutes. Compared with the demulsifier currently used in the field, MF-4 reduces the dosage by 14.3% and shortens the residence time by 16.7%. The synthesized MF series multi-branched fluorinated polyether demulsifier exhibits excellent demulsification performance, significantly enhancing oil-water separation efficiency and meeting the efficient treatment requirements of chemical flooding produced liquid in offshore oilfields.