In order to guarantee the stability of excavation surface of mined tunnel, dewatering should be carried out before excavation. The filter layer used in conventional tube well dewatering technology is backfilled by permeable materials after excavation, which would lead to waste for weathered granite. As a result, the conventional tube well dewatering technology is improved. The soil around the tube well is directly used as the permeable materials, and the inverted filter is formed automatically by high-pressure wind, forming a new dewatering technology, which reduces the processes of filter layer wrapping and filter layer backfilling. The dewatering technology is applied to the underground tunnel construction of Xiamen Metro Line 4. According to the calculation results, 2. 92 m3 per hole of filter material can be saved and about 10 h of construction time can be reduced. The pollution to the surrounding environment is small and the environmental protection effect is outstanding as well.