Abstract: The water radon and water mercury data observed from Wang Third Well from the beginning are processed systematically.Through analysis we concluded that the decline in annual variation of water radon and the drop of water mercury in Wang Third Well are relevant to the digitalization reconstruction of the well,and the decline of water radon and mercury in the second half year of 2004 is relevant to the water extraction in Zhouliang First Well.Some reconstruction measures to Wang Third Well are presented,and the question to choose new observation well for hydrochemistry in Tianjin is also put forward.