The hydration resistance of CaO materials prepared by Ca(OH)(2) calcination with titanium chelating compounds is investigated in this paper. The crystalline phases and microstructure characteristics of sintered specimens were studied by X-ray diffraction (XRD), define FTIR spectroscopy, scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). The results showed that the hydration resistance of CaO samples was improved significantly, especially for samples with 9 wt% Ti chelating compound. The specimens with Ti chelating compound showed an increase in bulk density and a decrease in apparent porosity after heating when compared to the specimens without additive. The grain surface of CaO grain and the gaps between the CaO grain boundaries were covered with calcium phosphate glass phase, calcium phosphate showed two different shapes: irregular shape and rod shape. The formation and distribution of these two forms were the key factors that affecting the hydration resistance of CaO samples.