Abstract：In the sublevel caving longwall face 8103 of Tashan coal mine，an abnormal phenomenon that time of micro-seismic wave transmitting to bottom hole geophones far from the hypocenter was shorter than that to roof hole geophones near hypocenter. According to classical model of micro-seismic wave transmission，the energy consumption and transmitting time of micro-seismic wave induced by roof through separation layers and coal seam to bottom hole geophones must be larger. In order to explain the phenomenon，it was assumed that new hypocenter was formed at the interface between bottom floor and coal seam when micro-seismic waves induced by immediate roof or main roof passed through the entrance interface of coal seam and bottom vertically. Transmission direct assumption explained the phenomenon that remote point reached first on the basis of sufficient research on stress history and support effort，etc.. In-situ experiment of calibration blasting confirmed that obtained time difference according to the assumption was equal to true reach time difference approximately. So transmission direct assumption could be used in hypocenter localization and checking. It also could be used for improving location precision.
