The effect of inorganic salts on the cloud point temperature of aqueous PEG was measured by laser method. It was found that there is a linear relationship between the cloud point temperature and salt concentrations while the concentration of salt is low Tc = T0 + Km The experimental results indicate that the lower critical solution temperature (LCST) of PEG 10000 is 115±0. 5℃

and the critical composition is 11. 5 wt% PEG.