Simultaneous extraction of basic and non-basic N-compounds from oil is still a big challenge. Triethylene glycol (TEG) encounters very weak Brønsted acidity. Its N-distribution coefficient [D N, (mmol·gEx –1)/(mmol·gOil –1)] for the basic was below 7.0. In this work, metals dissolved in TEG can improve the Lewis acidity of the extractant and bring about the simultaneous removal. For example, D N of TEG–Ag­(I) can increase to 40.5 for quinoline and 57.9 for pyridine, respectively. For the non-basic, it still remained higher than 70.0. The promoted performance was ascribed to the improvement of extractive behavior of the basic. From TEG to TEG–Ag­(I), first, the distribution of equilibrium N-concentrations between two phases was significantly changed from the straight line to the non-linear curve with the plateau. Second, the interaction type inside the system was optimized. The Ag­(I)-based complexation coupled with the TEG-based H-bonding was identified. Third, the interaction intensity was increased as well. Ag­(I) contributed much to reduction of Gibbs free energy change for the basic. Therefore, enhancing Lewis acidity of the extractant was a feasible way for the extraction of the N-compounds.