The solidification of ettringite on the chromium ions with different valence states and species under the condition of different sulfate concentrations were investigated by means of XRD, IR analysis, DSC, SEM, ICP and other method. The results showed that the ettringite solidification rate for the low dosage(05%) of chromium ions with different valence and species was add up to 85% or more. The solidification rate of ettringite to Cr(Ⅲ) changed little, while the solidification rate to Cr(Ⅵ) 28d decreased to 386% when the dosage of chromium ions increased to 20%. The solidification ability of ettringite to Cr(Ⅵ) was improved when the concentrations of SO2-4 ions were low in the hydrated liquid phase. No matter what concentration of SO2-4 ions was in the hydrated liquid phase, Cr(Ⅲ) and Cr(Ⅵ) had a different effects on the crystal structure and morphology of ettringite, and that of Cr(Ⅲ) was more obvious. The effect of Cr ions on ettringite crystal morphology was also different. When the concentrations of SO2-4 ions were low in the hydrated liquid phase, the doping of Cr(Ⅲ) could obviously promote the growth and development of ettringite crystal in the c axis direction, and improve the crystallization degree and thermal stability of ettringite to a certain extent.