The microstructure development of cement stone is an important reference for cementing process design and cementing quality evaluation.Based on the software hymostruc3d, the hydration model of cement was established, and the ch content and compressive strength were obtained. The experimental results were compared. The deviation between the simulation results and the experimental results was basically within 10%.Then, based on the cement hydration model, the effects of different water cement ratiosW/C (W/C = 0.4, 0.44, 0.5, 0.6, 0.8, 1.0, 2.0) and hydration age on C3S, C2S, C3a, c4af, C-S-H, CH, porosity, pore size distribution, compressive strength and three-dimensional structure of cement slurry were obtained based on cement hydration model.At the same time, ryshkewitch equation, Schiller equation and quadratic linear equation are used to discuss the relationship between compressive strength and porosity.The results show that: in the process of cement hydration, with the hydration reaction, the porosity of cement paste decreases gradually, and the compressive strength increases; with the increase of water cement ratio, the content of coarse pores increases, the proportion of fine pores decreases, the porosity increases, the pore size distribution widens, and the compressive strength decreases.Using ryshkewitch equation, Schiller equation and quadratic linear equation, the correlation coefficients between compressive strength and total porosity and capillary porosity are all above 0.92, which are 0.96, 0.92, 0.95 and 0.98, 0.97 and 0.98 respectively. Capillary porosity is the main influencing factor of cement strength developmen.