The solubility of L-phosphinothricin (L-PPT) and its hydrochloride in water + (methanol and ethanol) binary solvent mixtures was experimentally measured from 278.15 to 318.15 K by a static analytic method under atmospheric pressure. The experimental data showed that the solubility increased with the increasing temperature and decreased with the increase of alcohol concentration in binary solvent mixtures. The experimental data were correlated by the modified Apelblat equation and combined nearly ideal binary solvent/Redlich-Kister model. The results indicated that the modified Apelblat equation showed better agreement with the experimental data. The parameters characterizing preferential solvation of L-PPT in water + methanol binary solvents had been calculated. The results showed that the preferential solvation of L-PPT was related to the solvent composition and temperature.