In order to understand the modification effects of α and γ type nano-Al2O3 on the cement base material, the 30 nm α and γ type nano-Al2O3, Yaobai cement, standard sand and carboxylic acid water reducing agent were used to make cement base materials, the setting time, mechanical properties and shrinkage performance and their mechanism were analyzed. The results showed that: The setting time of cement base material can be reduced, the flexural strength and compressive strength of cement base material can be improved, and the drying shrinkage of cement-based materials can be reduced when nano-Al2O3 of α and γ type replace cement. But the modification effect of α type nano-Al2O3 on cement base material is lower than the γ type. Based on the analysis of this article and literature review, we found that nano-Al2O3 of α and γ type in cement base material plays the roles of size effect, filling effect and surface effect, which will achieve the ideas that modified mechanical properties and durability of cement base material.