Abstract: The plain area in Pinggu is a major groundwater source for Beijing.To ascertain the spatio-temporal distribution of groundwater in the study area without damaging the strata,this study,using the non-intrusive time-lapse resistivity method,conducted the reciprocal measurements with Wenner and dipole-dipole arrays in Beiyangjiaqiao Village,Pinggu District.The least-squares inversion results of the profile observation data and normalized data show that:(1)the phreatic and confined aquifers in the study area are approximately horizontally stratified,with the phreatic aquifer being recharged from the north and flowing from north to south;(2)during the entire observation period,the phreatic aquifer showed a drop in water level and leakage into the confined aquifer below;(3)the water content in the aeration zone increased from April 24,2021 to September 12,2021.In contrast,the water content in the confined aquifer remained relatively stable in this period,without experiencing significant changes.The results of this study lay the foundation for the subsequent research on Quaternary strata and groundwater in the study area.Moreover,they can be used as an important reference for the development,management,and utilization of groundwater in the study area and provide a new philosophy for research on the dynamic process of groundwater.