Abstract: Based on summing up, in microscopic scale, of a part of resarch results concerned inside and outside our country and some seismic data, we have preliminarily analysed and discussed the probability that the changes of the physical chemistry property and state of groundwater itself and its solutiowhich are caused by outside environmental factors such as temperature, presn sure and so on might result in a change of water volume and then cause a change of water level.That is the physical chemistry mechanism of water level change of thermowates.