The decreasing of oil production has become the main factor for applying Enhanced Oil Recovery (EOR) methods in the oilfield. Chemical injection using surfactant was one of EOR technologies that had been proved to increase the oil recovery. In this study, surfactant was synthesized using palm oil as hydrophobic group and polyethylene-glycol as hydrophilic group. The use of natural oil as the raw material was preferred used due to its abundant and environmentally friendly. Esterification of nonionic surfactant was performed by utilizing the azeotrope technique (EtOAc-H2O) between oleic acid and polyethylene glycol (PEG) 400. The reaction was optimized by a various mole equivalent of oleic acid and PEG (1:1,1; 1:2,5; 1;3) in various reaction time. Surfactant product was characterized by thin-layer chromatography (TLC), acid value (AV), and ester value (ES) to determine the optimum condition and conversion rate. The molecular structure of surfactant was confirmed by ¹H and ¹³C Nuclear Magnetic Resonance (¹H and ¹³C NMR) and Mass Spectroscopy (MS). Then, nonionic surfactant was analyzed by measuring the interfacial tension (IFT) of oil and water. The optimum condition was achieved by reacting oleic acid and PEG at mole equivalent ratio of 1:3, 5 hours reaction time, and conversion rate of 93.7% mole. This nonionic surfactant was able to decrease the IFT of oil and water as low as 10-3 dyne/cm in brine salinity condition of 18000 ppm and oil 34,39°API.