The study was carried out to estimate the efficacy of the predatory mite Neoseiulus cucumeris (Oudemans) to control the whitefly pest Bemisia tabaci (Gennadius) in plastic greenhouses. N.cucumeris could prey on all stages of B.tabaci. The predator could be effective in suppressing B.tabaci and thus can be a potential biological control agent; Four～six releases of N.cucumeris were done during the 250 days of growth cycle of eggplant unde these conditions, at rates of 5~10 individuals per plant at seedling stage, and 20~40 individuals per plant at fruiting stage resulted in eliminating 18 chemical applications with resepct to chemical control in greenhouse; The key to successful biocontrol was Integrated Pest Management including the cleaningfield, the flynte and the timing of releasing N.cucumeris. The efficiency of the biocontrol would be better if the yellowboard was applied.