Electroantennogram (EAG) responses to several chemical volatiles of soybean plant were investigated for the following four species of insects: 1) Aphis craccivora Koch and Macrosiphum avenae (Fabricius); 2) Lysiphlebus fabarum Marshall, the common nature enemy of Aphis glycines Matsumura which is the pest insect of soybean plant, and of A. craccivora which is not the pest insect of soybean plant; 3) Aphidius picipes Nees, the nature enemy of M. avenae which is not the pest insect of soybean plant. The results showed that L. fabarum related indirectly with soybean plant in nature was sensitive to the tested volatiles and their mixtures; the rest three species of insects irrelative to soybean plants in nature were not sensitive to the volatiles and their mixtures. This suggested the important function of plant volatiles in host searching of natural enemies of the phytophagous. none