Abstract: Without chemical control , the communities of vegetable insect pests and their natural enemies had apparently dynamic relationships. In Jianghuai area , the pest community mainly included B revicoryae brassicae , Tet ranychus cinnabarinus , Diaphania indica and Myzus persicae , while the natural enemy community chiefly composed of Harmonia axyndis , Coccinella septempunctata and Trichogramma evanescens. Number of species and individuals of insects reached a climax between late August and late September , and the indexes of evenness and diversity of insect community were above 2. 5 and 0. 7 respectively. The authoritative coefficient between the communities of pests and natural enemies reached significant level. The the correlation between the two communities was mainly dependent on the index of diversity and evenness , which had higher values loading in correspondent communities.