Abstract: There are water-bearing karst areas in Guangzhou, Shenzhen and other cities. The groundwater is rich, and the development form is complex. It is easy to cause safety accidents such as water inflow and collapse during subway construction. Relying on a subway station project in Guangzhou, the site permeability coefficient is 6.32 m/d through the field pumping test, and the total water inflow of the foundation pit is predicted. Two process tests are carried out using numerical simulation, and the final state error of dewatering is 14.92% and 7.08%, respectively.The results are ideal. The influence rules of different forms of water-bearing karst caves on the stability of foundation pit are further studied, and the sensitivity analysis of various influencing factors is carried out based on the grey correlation theory. The groundwater level and the water pressure of the cave have a greater impact on the horizontal deformation of the envelop enclosure, with the sensitivity of 0.946 and 0.925 respectively. The spacing and water pressure of the cave have a great impact on the ground settlement, with sensitivity of 0.999 and 0.975 respectively.The spacing and diameter of the cave have great influence on the maximum tensile stress of the support structure and the pore water pressure of the foundation base.