Abstract: Based on the high density resistivity method which is widely used in engineering survey，this paper used a special auxiliary grounding device to solve the ground obstacles of this method in the bedrock exposed area of the mine，and then this device has been applied to detect a known fault and an underground mined-out area in mining area.The interpretation results from the data show that high density resistivity method is feasible and efficient in finishing this type of survey.

Key words: High density resistivity method, Geologic disasters in mine, Grounding device, Fault, Mined-out area