Groundwater's studies at middle Kert aquifer in northeast of Morocco are very important due to the semi-arid character and its geological history. The region is recognized by messinian salinity crisis already 5.6 Ma. Water chemistry is mainly dominated by dissolution of evaporate rocks (Halite and Gypsum) related to outcropping and basement limits developed in Messinian age. Freshwater with total dissolved solids 740 mg/l (average value) in Tafersite district is chemically distinct from saline water with total dissolved solids of 9803 mg/l in the south zone. In wadis, water is S04-Cl-Ca type; they are influenced by the surrounding highlands located at the south of the plain. The investigation reveals that weathering of evaporated rocks is the processes responsible for high Na+, Ca2+, Mg2+, Cl andSO42- concentrations. Also, hydro chemical data displays that freshwater observed in the northwest part reflect the influence of freshwaters coming from metamorphic massive of Temsamane. The factorial analysis reveal three sources of salinization, the principal one is described above, whilst the dissolution of carbonates and human influence represented by NO3- played only a secondary role.