Abstract: The dynamic detection technology of coal seam thickness is an essential prerequisite for improving the local model accuracy of coal seam and realizing the intelligent accurate mining.However,now the coal thickness detection mainly focuses on the thin coal seam and rarely involves the extra-thick coal seam,also a single dielectric constant is often used to calculate the thickness of coal seam,moreover,the detection methods mainly refer to static and single point measurement.The above factors will lead to the detecting results with low efficiency and uncontrollable accuracy between the measured points.Therefore,to improve the modeling accuracy in local model of extra-thick coal seam,it is urgent to investigate the dynamic detection technology for extra-thick coal seam in the headings of working face.For this reason,this paper proposes the coal-rock interface identification technology based on bandpass filtering,the dielectric constant accurate calibration technology for coal seam,and the detection data location technology using time synchronization.The above proposed technologies will be used to realize the dynamic measurement of extra-thick coal seams thickness.The main contributions of this paper can be summarized as follows: firstly,the static detection is conducted to obtain the coal-rock interface data at the location of borehole using ground penetrating radar,then both borehole data and radar detection information will be used to calibrate the dielectric constant of coal seam.Secondly,the interpolation method is applied to calculate the dielectric constant of coal seam between two adjacent boreholes,the coal thickness dynamic detection between two boreholes will be obtained using ground penetrating radar combined with microcontroller and accelerometer measuring information.Then,the moving displacement of ground penetrating radar is calculated accurately,which will be calibrated by the existed marked distance information in underground roadway.Finally,the detection data is matched with the displacement based on the principle of time synchronization,and the accurate location of ground penetrating radar detection data is realized.The coal thickness information in each detection position is calculated by using the calibrated dielectric constant and the detection data with displacement information.The test results in Tashan coal mine show that the dynamic detection errors of extra-thick coal seam are less than 10%,which meets the requirement of vertical modeling accuracy of three-dimensional coal seam model.It is also proved that this method can dynamically detect the thickness of extra-thick coal seam.