Abstract: The study showed that Lycosid (wolf spider) mainly distributed in the basal part of rice plants,not as wide as we know in past.Tetragnathid did not limited in the upper part of plants,but might translate to middle or lower part when affected by insecticide.The relationship between the vertical distributions of top and basal species was not significant.Besides the amount of natural enemies,the spatial distribution characteristics of natural enemies and brownplanthopper,and the proportion of brownplanthopper to total preys of natural enemies were the factors affecting the role of natural enemies on the population dynamics of brownplanthopper in rice fields.A model to evaluate the effect of natural enemies to brownplanthopper was put forward,which included the messages of quantitative dynamics,spatial distribution and feeding characteristics of natural enemies,brownplanthopper and neutral insects.