Abstract: Land subsidence in Tianjin occurs in a wide region and at a great rate.Since the lack of reconnaissance and the impossibility of groundwater-exploitation forbid have been the major problems and can not be solved at present,a new term called the "ratio of soil loss to groundwater-exploitation" is recommended in this article.From the conception and calculation of the ratio,it is clearly seen that the ratio can be used to test the veracity of statistical data on groundwater-exploitation,indicate the condition of groundwater recharge and drainage from clay soil,and reflect the seriousness of land subsidence and the guarantee of groundwater resources.In addition,it is an advocate to use the ratio to achieve the rational amount of groundwater exploitation with correlation analysis.