Abstract: Aiming at the disasters of water burst or seepage during construction or operation of underground works and making full use of the properties of non-water-reacting polymer grouting material and its application technology, this study develops new treating methods: membrane-bag closure against pressure grouting in the water burst cases and tube grouting against seepage. We demonstrate the surrounding rock reinforcing effect of polymer grouting and its blocking, filling and diffusing effects in the condition of dynamic water pressure sealing, by using numerical analysis and the concepts of polymer rheological dynamics, fluid mechanics, material forming technology, and molecular mechanics, and by considering the procedure of seepage sealing and its long-term effects on surrounding rock. Our methods are applied to a variety of practical treatments against water burst and seepage: tunnels in construction, tunnel boring machine (TBM) shield tunneling, reservoir spillways in operation, open cut tunnels, subway stations, underground commercial development, and underground passage works. The results show that non-water-reacting polymer grouting is efficient, fast, and of long durability in solving the seepage problems of underground engineering, thus providing a new approach for seepage treating technology.