Abstract: Bedrock fissure water is one the groundwater types,distributed widely in China.In this paper such features of bedrock fissure water as abnormarity of aquifers in occurrence,nonhomgeneity of space environment in Which they occurred,difference of the same aquifer in occurrence depths,and complexity of groundwater motion conditions are described.These special geological and giopysical features bring difficulties to conventional geopysical methods of detecting groundwater.By contrast of the new NMR directly detecting water method with resistivity method of indirectly detecting,water the nature of NMR detecting water method is elucidated,and effect resulted from using NMR sounding to detect bedrock fissure water shown with some examples.