Disperse condition of nano clay in cement has a great effect on the property of the cement based materials. Disperse method, disperse time and the amount of the additives are the major effective factors. The effects of the disperse method on the property of nano clay modified cement were examined through some micro testing techniques(such as XRD, SEM and MIP test, etc). The influence of nano clay additives on the flexural strength of modified cement was investigated. The optimum additive was recommended. The results show that long duration dispersion with machine is a beneficial way to improve the disperse condition of nano clay in the cement based material.It is concluded that the addition of nano clay will improve the strength of the cement at early age. Comparing with the normal cement, the flexural strength of the cement with 3.00%(by mass) nano clay additive will increase 21.64% at 14 days, and will increase 25.94% at 90 days.