Abstract: In order to meet the special requirement of L-borehole ground pre-grouting technology on grouting material, the mix proportion of bentonite-silicon powder stabilizer is determined by orthogonal test, the optimum ratio of single liquid cement base composite grouting material is proposed by comparatively studying the stability effect of two different retarders on cement. By the comparison test, it is proved that the single liquid cement base composite grouting material can guarantee good pump-ability and improve the compressive strength and could be applied to the L- borehole ground pre-grouting with good effect.