Abstract: Groundwater monitoring wells tapping deep confined aquifers in the Zhejiang coastal plain commonly suffer from low flushing efficiency, limited effective cleaning range, and incomplete removal of deep clogging materials. This study aims to improve the precision and efficiency of well flushing through technological innovation. Based on the limitations of traditional piston flushing techniques, such as significant energy attenuation and aquifer disturbance, an innovative oscillating well flushing technology integrating a section-sealed piston and mud pump is proposed. This approach combines the mechanisms of section isolation, water hammer effect, and seepage synergy. Expandable rubber packers are utilized to precisely isolate target well segments, while the synergistic interaction of high-frequency suction (−0.3～−0.2 MPa) from the mud pump and piston pulling (0.6～1.2 m/s) generates alternating positive-negative pressure oscillations. Optimized dynamic segment isolation (2～ 4 m per segment) and three-stage pressure regulation (0.2～2.0 MPa) effectively remove wellbore mud cake and filter layer clogging materials. Field validation via the Jiaxing groundwater monitoring network project demonstrates that the improved technology reduces flushing time by 40%～50%, increases permeability coefficient by 15%～35%, and enhances single-well yield by 20%～30%. Flushing fluid recycling efficiency is improved to 60%–65%. Moreover, the segment isolation design reduces hydrogeological parameter inversion errors from 15%～25% to 5%～8%, significantly improving groundwater model calibration accuracy. The technology integrating mechanical disturbance with dynamic negative pressure regulation, reduces carbon emissions by 35%～40%. The method provides critical technical support for coastal groundwater monitoring well construction, resource management, and land subsidence control, and presents strong potential for broad application in deep confined aquifers.