研究了二嗪磷与Ｂ．ｔ制剂混配对小菜蛾幼虫的共毒作用，结果表明：混配剂在作用前期（２５℃１ｄ，１６℃２ｄ）表现一定程度增效作用，而在作用后期（２５℃２ｄ，１６℃３ｄ）则表现二种单剂的相加作用．当二嗪磷在混配剂中的含量降低或处理温度较低时，前期增效作用更为显著。小菜蛾幼虫龄期对其共毒作用无明显影响。 Diazinon and B were studied. t formulation to the diamondback moth larvae. The results showed that the mixture had a synergistic effect in the early stage (25 ℃ 1d, 16 ℃ 2d), while in the late stage (25 ℃ 2d, 16 ℃ 3d) The performance of two kinds of single additive effect. When the content of diazinon in the compounding mixture is reduced or the treatment temperature is lower, the synergism is more significant in the early stage. The larval age of Plutella xylostella had no significant effect on its co-toxicity.