Chloride saline solution have been extensively studied for its widely exists in seawater and saline lake,but ionic association characteristics in some mixed saline solutions are still unclear.LiCl dissolves well in water because of the strong difference in the ionic radius between lithium and chloride ions[1].Meanwhile Mg2+ has an ionic radius similar to that of Li+,and thus these two ions exhibit similar physicochemical properties,which brings obstacles to the study of the mixed saline.In this work,we investigated the ionic characteristics of LinClm and MgxCly in mixed LiCl-MgCl2 solution.Results of classical MD simulations showed that the size of MgxCly ion cluster in the MgCl2 supersaturated solution becomes smaller as the addition of LiCl,as shown in Figure 1.We also found that the largest cluster survives only a moment whose lifetime is 0.4ps in the MgCl2 supersaturated solution.On the contrary,in the binary system the largest ionic cluster widely exists,and the longest lifetime is 0.6ps,which indicated that the largest cluster becomes slightly more stable.Similarly,the size of the largest LixCly ion cluster also slightly decreases in the supersaturated LiCl solution as the addition of MgCl2.In addition,the ionic characteristics in MgCl2 solution under various temperature and pressure have also been discussed.The ionic characteristics in MgCl2 solution do not change as pressure increasing,while ionic cluster size decrease obviously with the temperature increasing.This phenomenon is different from that of most other ions,but consistent with the result of Karan M[2],which found no contact ion pair(CIP)even in the highly concentrated aqueous solution with the Raman spectroscopic study.