Plant endophytic fungi share photosynthetic plants as food and energy sources with insect herbivores and play critical roles in shaping community structure and dynamics, driving evolution and promoting plant production. This review summarizes current progresses on endophytic fungi-plant symbionts, effects of endophytic fungi on insect herbivores and natural enemies, and endophytic fungi-produced antiherbivore metabolites. It is suggested that plant endophyotic fungi should be weighted on the studies of plant and insect ecology and crop integrated pest management.