Abstract: Natural penetration tests intuitively show the chloride diffusing process in concrete.The calculation models for chloride diffusion coefficients are discussed in this paper.The analysis results show that: chloride diffusing into concrete is a complex process of physical and chemical effects,and the diffusion coefficients are the time-dependent functions,and the attenuation coefficients are related to cementitious materials,water cement ratio and exposure environment.According to model Ⅱ,for short term soaking experiment,the influence of a curing age and soaking time on the chloride diffusion coefficient calculation results cannot be neglected,whereas,for long term immersion experiment,namely when soaking time is far longer than the curing age,its influence can be neglected.