The concentrations of lithium and strontium of highly concentrated lithium-strontium mixed solution were determined simultaneously by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). After considering total salinity, relation coefficient and intensity at different wavelengths of lithium and strontium respectively, the determination wavelength was chosen for lithium and strontium separately. Using the determined wavelength, the result varies in terms of acid effect, equipment operating parameters and total salinity in the mixed solution. When the total salinity was in the range of 0.20%～0.60%, the linear correlation coefficient of Li and Sr was better than 0.999 9. After optimizing the instrument parameters, the standard solutions relative errors were within +0.59%～-0.66%, and the samples recoveries were within 99.14%～100.4%. This method is reliable due to stability and good recurrence. It can be used to determine high concentration of lithium and strontium ions in the lithium-strontium mixed solution accurately and rapidly.