Based on life table method,the controlling effects of 6 insecticides and Batrytis(Beau-weria Vuill.)on the natural population of Masson pine caterpillar(Dendrolimuspunctatus Walker)were evaluated by Interference Index of Population Control(IIPC). IIPC reflecfs both the key effects of measurements and the side effects of insecticideson natural enemies,and can hence comprehensively evaluate the influence ofcontrolling measurements on insect population dynamics. It is stated from the exper-imental results that,specific action insecticide and Batrytis have better interferencingeffects on Masson pine caterpillar than others;and the broad spectrum insecticides arehelpful to heavy outbreak of the natural population of Masson pine caterpillarin next generation.