As the main water supply source of Suzhou，groundwater plays an important role in social and economic development. The shallow pore groundwater and middle—deep pore confined groundwater are the main water- bearing rock groups in the study area. Through a comprehensive consideration of the test results of groundwater samples and hydrogeological conditions of Suzhou，this paper aims at studying the hydrochemical characteristics and control processes of groundwater at different depths in urban district of Suzhou.Methods：37 groups of shallow pore groundwater samples and 13 groups of middle pore groundwater samples were collected to measure its cation and anion，total dissolved solids. Statistical techniques，correlation analysis，Piper triangular diagrams，Gibbs figures and ion ratios were used to analyze the test results of samples.Results：① The major cations in shallow and middle-deep groundwater are dominated by Ca2+ and Na+，respectively，and the dominated anions are all HCO3-. The average values of TDS in shallow and middle groundwater are 790.65 mg/L and 585.67 mg/L respectively. Three groups of shallow groundwater samples are brackish water，while the remainder and all the middle-deep groundwater samples are fresh water. ②The hydrochemical types of the shallow groundwater are complex，mainly with HCO3-—Ca2+·Mg2+ and HCO3-—Na+·Ca2+·Mg2+ type，and followed by HCO3-—Na+·Mg2+ type. The middle-deep groundwater is showing the HCO3-—Na+·Ca2+·Mg2+ type.Conclusions：The hydrochemical characteristics of groundwater in urban district of Suzhou was influenced by dissolving filtration，cation exchange and human activities，the hydrochemical components of groundwater mainly came from the weathering and dissolution of silicate and carbonate minerals. The shallow groundwater was greatly affected by human activities，while the middle groundwater was not obviously.