Sodium chloride (NaCl) is one of the key components of atmospheric aerosols. The surface tension of aqueous NaCl solution (σ<sub><I>NaCl,sol</I></sub>) and its concentration dependence are essential to determine the equilibrium water vapor pressure of aqueous NaCl droplets. Supersaturated NaCl solution droplets are observed in laboratory experiments and under atmospheric conditions, but the experimental data for σ<sub><I>NaCl,sol</I></sub> are mostly limited up to sub-saturated solutions. In this study, the surface tension of aqueous NaCl is investigated by molecular dynamics (MD) simulations and pressure tensor method from dilute to highly supersaturated solutions. We show that the linear approximation of concentration dependence of σ<sub><I>NaCl,sol</I></sub> at molality scale can be extended to the supersaturated NaCl solution until a molality of ~9.6 mol kg<sup>−1</sup> (i.e., solute mass fraction (<I>x<sub>NaCl</sub></I>) of ~0.36). Energetic analyses show that this monotonic increase of surface tension is driven by the increase of excessive surface enthalpy (∆H) as the solution becomes concentrated. After that, the simulated σ<sub><I>NaCl,sol</I></sub> remains almost unchanged until <I>x<sub>NaCl</sub></I> of ~0.47 (near the concentration upon efflorescence). The existence of the <q>inflection point</q> at <I>x<sub>NaCl</sub></I> of ~0.36 and the stable surface tension of <I>x<sub>NaCl</sub></I> between ~0.36 and ~0.47 can be attributed to a competitive growth of excessive surface entropy term (T · ∆S) and the excessive surface enthalpy term (∆H). After a <q>second inflection point</q> at <I>x<sub>NaCl</sub></I> of ~0.47, the simulated σ<sub><I>NaCl,sol</I></sub> gradually regains the growing momentum with a tendency to approach the surface tension of molten NaCl (~148.4 mN m<sup>−1</sup> at 298.15 K, MD simulation based extrapolation). This fast increase of σ<sub><I>NaCl,sol</I></sub> at <I>x<sub>NaCl</sub></I> > 0.47 is primarily still an excessive surface enthalpy-driving process, although contribution from concurrent fluctuation of excessive surface entropy is expected but in a relatively smaller scale. Our results reveal different regimes of concentration dependence of the surface tension of aqueous NaCl at 298.15 K: a water-dominated regime (<I>x<sub>NaCl</sub></I> from 0 to ~0.36), a transition regime (<I>x<sub>NaCl</sub></I> from ~0.36 to ~0.47) and a molten NaCl-dominated regime (<I>x<sub>NaCl</sub></I> from ~0.47 to 1).