Water temperature gradient in Xinji well has been tested from 50m to 200m deep,and the results show that there are 3 negative gradient sections(50-60m,90-110m,130-140m)in the test depth. The clear water temperature tide,whose phase is in contrast to the water level tide,has been found in 50m to 60m depth position in the water temperature negative gradient. According to the well drilling data and hydrogeological conditions,water temperature negative gradient may be associated with the cold water layer in the same depth around the well. Characteristics of the water temperature tide in the negative gradient have been discussed.