Abstract: Changes in ontogeny, morphological character, physiological state, nutritional quality and secondary chemicals of plant could be induced by prior damage. The induced changes might have general negative effects on the behavior, development, survival and fecundity of successively occurred phytophagous insects because a change will reduce plant nutritional value, stimulate plant to produce poisonous chemicals or release synomone attractive to their natural enemies. Induced plant resistance could be an on-off response, be turned onin a relative short time when plants are damaged to above a certain threshold and causes plant show an individual and population effect on phytophagous insects due to its transmission within a plant and between plants. Induced plant resistance is variable among plantspecies, varieties, individuals and developmental stages and could be influenced by plant density, damage position and level, soil fertility and water content. Two aspects in this area, the mechanism of plant causing induced resistance and its relative importance on controlling phytophagous insects, should be studied further for convincing conclusions in the future.