Abstract: Several physiological and biochemical indexes of leaves of Pyrus bretschneideri Rehd injured by Epitrimerus pyri (Nalepa) were measured. The results showed that, comparied with the normal leaves, the chlorophyll and soluble sugar of the infested leaves decreased by 50.05% and 19.86% respectively; and the soluble protein ,free amino acid， free proline, the activity of hydrogen peroxidase and the membrane permeability of the infested leaves increased by 29.17%, 21.59%,107.03%, 22.62% and 150.43% respectively by the means of the analysis of spectrum, chemistry and electric physics.

Key words: Pyrus bretschneideri Rehd Epitrimerus pyri (Nalepa) physiological variation