There are many caves in the foundation of a sludge pump house in Liuzhou. The stability of the cave roof is poor, and the thickness of most caves is less than 3m. It is easy for structures to sink, crack or even collapse, causing serious consequences. Based on the detailed analysis of the characteristics of karst caves, combined with the characteristics of municipal engineering, this paper uses pressure grouting method to reinforce karst cave foundation, and achieves good treatment effect, and accumulates successful experience of municipal engineering karst cave treatment.