The Xifeng hot spring in Guizhou Province is a famous health resort.The spring waterhas a temperature ranging from 53° to 56° with a constant flow of more than 1,000 tonsper day.All the spring vents emerge on both sides along a normal fault in the Dengyinglimestone of Sinian age.Water analysis shows that the spring water contains a number of mineral componentsbeneficial to human health.The concentrations of Hg and F are relatively high,but renderno immediate harm to human body.Radon contents in fresh spring water and steam are 11.14and 32.73 roaches respectively,as determined by a FD-105 Type electrometer calibrated witha radium standard source.The radium content in the spring water is only 3.66×10~(-13) g/l,indicating that radium occurs in the free state rather than as a product of radium decay.On the basis of tritium content data and environmental geochemical investigations,the springhas not been affected by any nuclear test,and its age is at least 30 yr.The formation of thespring can be explained by pereulating surface water down to great depth along fault cracks,being heated as a result of normal geothermal gradient and seeking its way out along thecracks in the Sinian dolomite under the pressure of overlying strata. The Xifeng hot spring in Guizhou Province is a famous health resort. The spring water has a temperature ranging from 53 ° to 56 ° with a constant flow of more than 1,000 tonsper day. All the spring vets emerge on both sides along a normal fault in the Dengyinglimestone of Sinian age. Water analysis shows that the spring water contains a number of mineral components beneficial to human health. These concentrations of Hg and F are relatively high, but render no immediate harm to human body. Radon contents in fresh spring water and steam are 11.14 and 32.73 roaches respectively, as determined by a FD-105 Type Electrometer calibrated witha radium standard source. The radium content in the spring water is only 3.66 × 10 ~ (-13) g / l, indicating that radium occurs in the free state rather than as a product of radium decay. On the basis of tritium content data and environmental geochemical investigations, the spring has not been affected by any nuclear test, and its age is at least 30 yr. the formation of thespring can be explained by pereulating surface water down to great depth along fault cracks, being heated as a result of normal geothermal gradient and seeking its way out along thecracks in the Sinian dolomite under the pressure of overlying strata.