A mathematical model describing a coexistence system which contains brown planthopper (Nilaparvata lugens) and four spiders (Pirata subpi-raticus, Oedothorax insecticeps, Clubiona japonicola, Bianor hotingchiehi) was studied by rotation composite design of quadratic regression in this paper. Effects of different density combinations of these species on numbers of prey were analysed through the model. Meanwhile, the submodel of several spiders growth in field was constructed and the state equation of the bro...