Abstract: The poisonous bait was one of the important methods used to control the red imported fire ant Solenopsis invicta Buren effectively. The controlling effects of different doses of 0.045% indoxacarb bait on different densities of S.invicta nests were revealed in this paper. And 4 models which described the relationship among the fire ant nest density,bait dosage and controlling effect were presented. The theory dosages of the indoxacarb bait in controlling fire ant were 3~6 g with treating single nest, and 25~30 g with broadcasting 100 m2.