The invention relates to a building method of a cement-based material pore size distribution model. By testing cement-based materials with different water-cement ratios w/c, different admixtures and different admixture numbers m corresponding to the different admixtures, test data of changes of pore size distribution of the cement-based materials along with age t is acquired, model fitting is performed, the relations between the model and the water-cement ratios w/c, the age t and the admixture numbers m of the admixtures are obtained, and therefore the cement-based material pore size distribution model can reflect influences of the water-cementer ratios w/c, the age t and the admixture numbers m of the admixtures on cement-based material pore size distribution. Besides, the invention relates to predicted application of the cement-based material pore size distribution model. By designing the cement-based material pore size distribution model, pore size distribution of a cement-based material with any water-cementer ratio w/c and the admixture number m of any admixtures can be acquired quite conveniently.