Abstract: On the basis of indoor experimental results, the factors affecting the autogenous volume deformation of MgO-involving (up to 4.5%) cement concrete are concluded. The results show as follows: Autogenous volume deformation of MgO concrete is closely relative to mix proportions, high water content will accelerate hydration of MgO, thus increases expansion of concrete; the addition of fly ash will suppress the expansion of concrete. Corresponding to the increase in strength, the expansion of MgO concrete decreases; adding lightly burnt MgO powder to concrete will improve the autogenous expansion of high strength concrete; when the MgO content is about 4%, the autogenous volume deformation of the concrete will be approximate to a constant at about two years and would dont affect the safety of a structure.