This research was carried out to investigate the seasonal occurrence of major pests and the effects of releases of natural enemies for biological control of the major pests in eggplant greenhouse. A total of 8 pest species in 7 families were identified. Among these pests, Myzus persicae, Aphis gossypii, Frankliniella occidentalis, Tetranychus urticae and Trialeurodes vaporariorum were the dominant species in eggplant greenhouse. Two aphid species occurred mainly from May to June, but their populations decreased rapidly from July. The population density of F. occidentalis was high from June to July and T urticae and T vaporariorum were abundant from July to September during the growing season of eggplant. In the trials of biological control of pests, aphids could be suppressed within the range of 87~97% by two times releases of Chrysopa pallens eggs. F. occidentalis and T. urticae could be suppressed within the range of 76~90 and 87~91 % by three times releases of Orius sauteri adults, respectively. The releases of C. pallens eggs and O. sauteri adults were as effective as three times applications of insecticides for the control of aphids, F. occidentalis and T. urticae from May to September.