Abstract: Using filter contact method,acute toxicity of carbofuran and dimehypo,single or combined,to earthworms（Eisenia foetida）were studied.Results indicate that earthworms show different symptoms and mortalities,under the two different pesticides,and the median lethal concentration of dimehypo and carbofuran is 17.19 and 54.06 μg·cm^-2,respectively,so that dimehypo is more poisonous to earthworms than carbofuran.When the two pesticides are combined,no matter whether under carbofuran at 94.35 μg·cm^-2 combined with dimehypo ranging from 0 to 25.16 μg·cm^-2 or under dimehypo at 15.73 μg·cm^-2 combined with carbofuran ranging from 0 to 62.90 μg·cm^-2,the earthworms show mainly the symptoms under carbofuran.Compared with the toxicity of either carbofuran or dimehypo,the combined toxicity of the pesticides may be lower or higher,but the effect of variation of dosage of the pesticides in the combination on the variation of morality of earthworms is smaller than that of a single pesticide of the corresponding dosage.