［M(H2O)n］+(M=Li, K) hydrated clusters have been studied by Mass spectra, Raman spectra and the theoretical calculation. ［M(H2O)n］+(M=Li, K) hydrated clusters ion peaks could be obtained by Mass spectra, which could speculate that their maximum hydration numbers are 12 and 13 in their aqueous solution respectively. The same concentration gradient LiCl and KCl aqueous solutions of Raman spectra have been discussed and compared, the ~3 208 cm-1 Raman spectra of water structure had obvious changes because of the hydration of Li+ and K+. Between the 0～2.0 and 0～2.5 mol·L-1 concentration range of LiCl and KCl aqueous solution, respectively, their differential Raman spectra of ~3 208 cm-1 negative peak integral strength decreased in a linear, and hydration increased gradually. While concentration was more than 2.0 and 2.5 mol·L-1, the decrease of ~3 208 cm-1 negative peak integral strength deviated from linear relationship, and began to appear association. Theoretical calculation of structure and Raman spectra of ［M(H2O)n］+(M=Li, K) hydrated clusters showed that Li+ and K+ would form their second hydrated layer while n>4 and n>6 respectively, and O—H stretching vibration occurred blue shift, hydrogen bonding structures should been destroyed, thus was in agreement with the experimental results.