The present study investigated the effect of CaO incorporation on the microstructure and autogenous shrinkage of ternary blend Portland cement-slag-silica fume. Samples having water-to-binder ratio of 0.25 with varying CaO dosages were prepared, and their properties were explored through compressive strength test, MIP, XRD, SEM, TGA and autogenous shrinkage. The results indicated that the incorporated CaO promoted the reaction of binder materials, thereby enhancing early compressive strength. Furthermore, the volumetric change occurring in the hydration of incorporated CaO compensated for early age autogenous shrinkage during formation of the internal rigid skeleton, showing significant reduction in shrinkage movement in the final stage. Meanwhile, the microstructure and corresponding compressive strength of the samples were significantly affected by the steam curing condition due to the excessive volumetric expansion of the matrix by the CaO incorporation.