The present study investigates the effect of addition of shrinkage reducing admixture on the hydration properties of cement pastes at different curing conditions.Four mixtures were prepared using 0, 1, 2 and 5 wt% addition of shrinkage reducing admixture of cement.These pastes were hydrated under two different condition, (i) curing in water at home temperature, about 20±2 ℃ and (ii) curing in harsh drying condition with relative humility of 30% and temperature of 35±2℃ up to test ages.The hydration process of cement at early ages was followed by heat flow calorimetry.DSC-TG, X-ray diffraction (XRD) and scanning election microscope (SEM) were used to study the properties of hydrated cement paste at the age of 7, 28 and 60days.The results show that the addition of shrinkage reducing admixture promote the hydration of cement pastes and the increase of long-term performance of harden cement pastes, even curing in harsh drying condition, since the effect of "keeping water"ability of it.The chemical bound water and CH content from hydration of cement increased with the addition of shrinkage reducing admixture.In addition, the present research clarified the influences of shrinkage reducing admixture on establish of initial structure of harden cement paste at early age and the development with age increasing.