Abstract: According as the principle of energetics, a series of computing method on plant ecological field was brought forward to research the species' interaction of Quercus liaotungensis Forest, Dongling Mountain, Beijing. The effect radius of ecological field on the population of Quercus liaotungensis was decided as 15 meters and the ecological interference of Fraxinus rhynchophylla and Lespedeza bicolor population has obvious heterogeneity.

Key words: ecological field, population of Quercus liaotungensis, effect radius