Influence of chloride solution concentration difference on scaling of concrete by the deicer salt was studied by changing the internal and external chloride solution concentration of concrete. The test results indicate that the chloride ion diffusion process matches the Ficks second law during the pre saturated period of samples in chloride solution. The chloride ion concentration distribution on the concrete surface is obviously affected by the freezing and thawing process when chloride ion concentration is low(3%,by mass)or internal and external concentration difference exists. The internal and external concentration difference significantly affects the salt frost scaling of concrete. When the internal concentration is lower than the external concentration, the concrete scaling reaches a maximum value, which is much greater than that of specimens tested with the chloride solution concentration of 3%, which is generally regarded as the highest concentration for concrete deterioration.