Superabsorbent Polymer(SAP)has emerged as a topic of considerable interest in recent years.The present study systematically and quantitively investigated the effect of SAP on hydration,autogenous shrinkage,mechanical properties,and microstructure of cement mortars.Influences of SAP on hydration heat and autogenous shrinkage were studied by utilizing TAM AIR technology and a non-contact autogenous shrinkage test method.Scanning Electron Microscope(SEM)was employed to assess the microstructure evolution.Although SAP decreased the peak rate of hydration heat and retarded the hydration,it significantly increased the cumulative heat,indicating SAP helps promote the hydration.Hydration promotion caused by SAP mainly occurred in the deceleration period and attenuation period.SAP can significantly mitigate the autogenous shrinkage when the content ranged from 0 to 0.5％.Microstructure characteristics showed that pores and gaps were introduced when SAP was added.The microstructure difference caused by SAP contributed to the inferior mechanical behaviors of cement mortars treated by SAP.