Abstract: The existence state and dispersion behavior of graphene oxide (GO) nanosheets in aqueous phase and dispersant were studied. It is found that the main reason for the large dosage, high cost and unstable and insignificant application effect of GO when it is applied to cement-based materials is that GO nanosheets are easy to agglomerate and cannot be evenly dispersed in the cement matrix. Amphoteric polycarboxylate dispersant (APC) and its composite with GO (APC-GO) were prepared. The result finds that GO no longer exists in the cluster state in APC-GO composite , and is mainly adsorbed on APC multi-chain molecules and presents a multi-chain dispersion state. The mechanical properties and durability of cement-based materials can be significantly improved by the addition of APC-GO composite with ultra-low content (mass ratio to cement) of GO of 0.0003%. SEM results show that cement-based materials have regular and compact microstructure morphology. The results show that GO can be uniformly dispersed in cement matrix and has regular regulation effect on the morphology and structure of cement hydration products. The research results have guiding significance for the application of GO.