In marine environment, complex environmental factors such as temperature and dry-wet cycles accelerate the transmission process of chloride in concrete, thus affecting the durability of concrete structures. It is of great significance to strengthen the research on the durability evaluation of concrete in this special corrosive environment. At present, a single index (i.e., chloride diffusion coefficient) is usually used to quantify the influence of environmental factors on the durability of concrete, which cannot comprehensively reflect the influence of environmental factors on the chloride ion transport process. Based on the Fick second law, we derived an analytical solution of the total amount of chloride ions entering the concrete from the diffusion flux, as the accumulated content of chloride. For the cumulative content of chloride, the quantitative index 'l value' of concrete chloride permeability was established, and then the comprehensive evaluation method of concrete durability was constructed when the two typical marine environmental factors of temperature and dry-wet cycle were concerned. The influence of environmental factors such as temperature and dry-wet cycle on the l value of concrete was analyzed. A linear relationship between the 28-d apparent chloride diffusion coefficient D28 and the maximum monthly average temperature Tmax and a linear relationship between the age coefficient m and the annual temperature difference ΔTy were revealed. Subsequently, a simplified calculation formula for the quantitative index l value of concrete chloride ion permeability with respect of effects like dry-wet cycle and temperature was proposed. This formula is suitable for evaluating the influence of complex environmental factors (i.e., temperature and dry-wet cycle) on the concrete chloride permeability.