In this paper,we used the digital minute observation data of water temperature in Rongchang well located in Huayingshan Fault zone of Chongqing city,to analyzed the dynamic characteristics of coseismic and post earthquake response of Rongchang well water temperature to 273 earthquakes(M_S≥7.0 in the world,M_S≥6.0 in Sichuan Yunnan region,M_S≥4.0 in Chongqing and its surrounding areas)from January 2008 to September 2021,in order to study the cause and mechanism of coseismic dominant direction of well water temperature. The following results are obtained:① The water temperature of Rongchang well shows good coseismic and post-earthquake response ability,which can be recorded from both near and far earthquakes. The coseismic response of the water temperature in the well occurs from deep to shallow,in which the response duration is directly proportional to the observation depth,and the response amplitude decreases with the increase of the observation depth. The duration of the coseismic and post-earthquake response of the water temperature of the well is often longer than that of the water level of the same well. ② Since the observation starts,the coseismic response direction of water temperature in Rongchang well keeps increasing,which suggests that the water temperature of a single well has a dominant response direction for the coseismic response of different earthquakes,and the coseismic characteristics of water temperature depend more on the influence of the observation conditions of the borehole itself. The rise of the dominant direction of the coseismic response of the water temperature in Rongchang well may be caused by the disturbance of the seismic wave,which causes a large amount of gas in the deep part of the well to release into the aquifer system along the fractures. ③ The coseismic relationship between water level and water temperature in Rongchang well for medium and far-field earthquakes is mostly positive correlation of synchronous rise or oscillation-rise,and the coseismic relationship for near-field earthquakes is the inverse correlation between coseismic water level decline and water temperature rise,which may be caused by the inconsistent change mechanism of water level coseismic response caused by near-field earthquakes and medium and far-field earthquakes. Finally,the seismic energy density e(r) causing coseismic variation of water temperature in Rongchang well is greater than 10^-5J/m³,while the seismic wave energy density e(r) causing the coseismic reverse change of water temperature and water level in Rongchang well is greater than 1J/m³.