In order to investigate the performance evolution of cement based materials from curing to in serviced utilization, a quantitative analysis was performed on the main phase and microstructure evolution of cement paste in the entire process of curing and leaching. Firstly, based on the mineral composition of cement and its hydration mechanism, a simplified model of cement hydration was presented to calculate the concentration of its main products. Secondly, by using Ficks law and the conservation law of mass, the diffusion model of main ions, such as K+, Na+, OH- and Ca2+, in the pore solution of cement paste in soft water was established. Finally, the model was verified via its calculated data and the experimental results in the present literature. On the basis of the above model, numerical analysis was performed to investigate the entire process of curing and leaching of cement paste slice specimen. Results show that the models can quantitatively analyze the ionic concentration in the pore solution, porosity distribution, calcium hydroxide(CH) and calcium silicate hydrate(C S H) gel contents in the entire process, and it can be useful for the quantitative design on the leaching resistance of cement based materials in soft water environments.