Abstract: Karst areas are well developed in Southwest China, and karst hydrodynamic disasters have a great impact on underground engineering construction. In order to solve the problems of low slurry retention rate of cement-sodium silicate plugging materials, the traditional cement-soidium silica slurry is modified by water-soluble vegetable gum. The mechanism of water-soluble vegetable gum affecting the properties of cement-sodium silicate plugging materials is studied. The influence mechanism of the water-soluble vegetable gum on performance of karst water inrush plugging materials is investigated from the perspectives of setting time, compressive strength, slurry retention rate, viscosity evolution characteristics, hydration process and microstructure. The experimental results show that: (1) The water-soluble vegetable gum can improve the dynamic water anti-dispersion performance of the slurry, and the retention rate of the slurry can reach 96.4%. (2) Through the modification of different water-soluble vegetable gums, the setting time of the cement-sodium silicate slurry can be adjusted, and its application range can be increased. (3) Guar gum improves the early strength of the slurry paste matrix, but decreases its later strength. Both xanthan gum and xanthan gum-guar gum decrease the compressive strength of the slurry paste matrix. (4) The water-soluble vegetable gum can inhibit the hydration process of cement-sodium silicate slurry and improve the dynamic water anti-dispersion performance through the high viscosity property of the water-soluble vegetable gum and the cooperation of the reactive group with the cation in the cement. (5) The cement-sodium silicate slurry modified by the water-soluble vegetable gum is used in the water inrush project of limestone mine in Karst area, which effectively solves the problem of high flow rate and high flow inrush of karst pipelines.