The surface tension of aqueous NaCl (σ) is investigated by molecular dynamics simulations from dilute to highly supersaturated solutions. The linear approximation of concentration dependence of σ at molality scale can be extended to the supersaturated NaCl solution until the solute mass fraction (x_NaCl) of ~0.39. After that, the σ remains almost unchanged until an x_NaCl of ~0.47. Then the σ gradually regains the growing momentum with a tendency to approach the surface tension of molten NaCl.