Abstract: The parasitism of natural enemy of pests is subject to the influence of natural factors，specially in the different forest ecological environoments．The luring experiments using eggs of tussah indicated：(a)in the pure masson-pine forest and mixed broadleaf-conifer forest population number of Trichogramma dendrolimi and Amblymerus tabatae were more prolific，but Anastatus sp．was very 10w；(b)in the mixed hardwood forest population number of Anastatus sp．was considerable，but Trichogramma dendroBmi and Arablymerus tabatae were very r are．Moreover，climatic factor had vast effect 0n natural enemy．Anastatus sp．had a adaptbility to climatic factot and fluctuations of population tended upward throughout the year．Trichogramma dendrolimi usually varied with climate and number of population octasionally declined to zero in the high temperature and xeric summer.In early spring Trichogramma wasp was sharply influenced by low temperature or rain．The more complex phytocenose compose the more abundant natural enemy community．Hence it may be realized that outbreak of pests can be controled by Stressing forestry management practice．