Based on the tested data of springs and groundwater samples, This paper contrasted the large number of historical tested data and analyzed the hydrogeological condition, and studied the characteristic variation of hydro-chemistry of Jinan spring and discussed the cause of variation of Jinan spring water by use of the theory of groundwater and geochemical cycle. The aim is to protect the water quality of Jinan springs and holding back this trend of variation.The conclusion is that the hydro-chemistry character of Jinan spring has changed greatly in recent 50 years and the main cause of variation is inappropriate protection and man-made pollution.