Abstract: The methods of foundation treated with jet grouting pile or cement-flyash-gravle pile(CFG) have been widely applied in civil engineering fields, but combination with jet grouting pile and CFG pile is relatively less in Guilin karst area, and the interaction mechanism between two kinds of piles is not very clear, need to be further studied. The composite foundation of CFG pile and jet grouting pile is put forward, this foundation can bring the superiority into full play of two kinds of piles.The engineering case shows that the application of the composite foundation in the complicated conditions of karst area has obvious technical and economical value.