Effects of NaCl concentration(by mass) on the solution absorption and degree of saturation in concrete, and the ice formation expansion ratio and pressure of solutions were investigated under freezing thawing cycles, and then mechanisms on the deicer frost scaling of concrete were analyzed. Results show that the equilibrium value of ice formation expansion ratio and pressure of solutions are significantly reduced with the increase of NaCl concentration, but the critical degree of saturation is obviously enhanced. The degree of saturation in concrete during freezing thawing cycles in NaCl solutions are obviously higher than that in water, and the increase in degree of saturation in the concrete mainly depends on the solution absorption during the freezing, and is not related to the thawing. The ice formation pressure in 2%6% NaCl solution is maximum, so the deicer frost scaling caused by NaCl solution with the low medium concentration is most serious.