Abstract: It has great academic and practical significance to study the influence of polluted river on its offshore groundwater environment where surface water is seriously polluted.Based on the field observation experiments in Kui River in Jiangsu province,the time-and spatial distribution rule on physical,chemical and biological change of pollutants such as COD_Cr,NH₄⁺-N,NO₃^--N, Cl^- infiltrating into groundwater is discussed.And the ability of river offshore soil and groundwater to remove pollutants is analyzed.The field data shows that the efficiency of river sediment and its offshore soil to remove COD_Cr is high, to remove NH₄⁺-N and NO₃^--N is higher, to decrease the concentration is low due to the transform of NH₄⁺-N and NO₂^--N into NO₃^--N, and to remove Cl^- is very low due to its conservative character.As a result, the influence of conservative pollutant on river offshore groundwater must be considered.