Abstract: In order to find out the hydraulic connection between Baotashan sandstone aquifer from the floor of coal seam and other aquifers in the Jurassic coalfield, the underground dewatering test is adopted. The Baotashan sandstone aquifer is drained with large water flow, and the groundwater levels of other aquifers are observed by long-time observation boreholes synchronously. According to the response of different aquifers water level to the dewatering process from Baotashan sandstone aquifer, it is determined that the cretaceous aquifer, aquifer between the coal seams and triassic aquifer have obvious hydraulic connection with Baotashan sandstone aquifer. According to the vertical and plane characteristics of groundwater hydrochemistry of each aquifer, it is considered that the Baotashan sandstone aquifer in the west of the coalfield has positive alternation and good runoff condition, and DF20 fault is the hydraulic connection channel between the Baotashan sandstone aquifer and other aquifers. Based on the analysis of the groundwater flow field of each aquifer, it is determined that the Baotashan sandstone aquifer and cretaceous aquifer feed the aquifer between the coal seam through DF20 fault.