It is very important to determine the extent of the fractured zone through which water can flow before coal mining under the water bodies.This paper deals with methods to obtain information about overburden rock failure and the development of the fractured zone while coal mining in Xin’an Coal Mine.The risk of water inrush in this mine is great because 40%of the mining area is under the Xiaolangdi reservoir.Numerical simulations combined with geophysical methods were used in this paper to obtain the development law of the fractured zone under different mining conditions.The comprehensive geophysical method described in this paper has been demonstrated to accurately predict the height of the water-flow fractured zone.Results from the new model, which created from the results of numerical simulations and field measurements,were successfully used for making decisions in the Xin’an Coal Mine when mining under the Xiaolangdi Reservoir.Industrial scale experiments at the number 11201,14141 and 14191 working faces were safely carried out.These achievements provide a successful background for the evaluation and application of coal mining under large reservoirs. It is very important to determine the extent of the fractured zone through which water can flow before coal mining under the water bodies.This paper deals with methods to obtain information about overburden rock failure and the development of the fractured zone while coal mining in Xin ’ an Coal Mine. The risk of water inrush in this mine is great because 40% of the mining area is under the Xiaolangdi reservoir. Numerical simulations combined with geophysical methods were used in this paper to obtain the development law of the fractured zone under different mining. conditions. The comprehensive geophysical method described in this paper has been demonstrated to accurately predict the height of the water-flow fractured zone. Results from the new model, which created from the results of numerical simulations and field measurements, were successfully used for making decisions in the Xin’an Coal Mine when mining under the Xiaolangdi Reservoir. Industrial scale experiments at the number 11201, 14141 a nd 14191 working faces were safely carried out. The achievements provide a successful background for the evaluation and application of coal mining under large reservoirs.