Abstract: A new sealing grouting material with two-step expansion is developed，considering the disadvantages of current sealing grouting material，including drainage of water，leaked after grouting slow solidification，solidification shrinkage，etc.，referring to the research result of high water content and aerocrete，with sulfo-aluminate cement，gypsum，quicklime as main material and citric acid，bentonite，aluminum power，various additives as accessories，through triangular plot and orthogonal experimental design method.If the material is mixed with water，the effective aerated reaction taking place between the initial solidifying point and the end solidifying point will promote the slurry volume expansion，then it will achieve the goals that the leakage of slurry in the segment of sealing grouting must have compensation and the cracks around the borehole must have plugging.once again the ettringite crystallization leading to micro expansion in solidification harden stage would contribute to the further compaction sealing of micro crack.Experimental tests showed that the material has a high water-cement ratio (1.2∶1)，quick-setting，early strength，excellent expansion (up 15%)，moderate intensity，high resistance to permeability etc.，and the condensation rate can be in accordance with the construction schedule well.The material has good application prospects in the field of sealing grouting.

Key words: Two-step expansion, Grouting material, Mixing ratio, Performance parameter