In a pot experiment,pots of maize inoculated with G.intraradices Schenck & Smith and G.etunicatum Becker & Gerdemann were treated with herbicides.The dosages of herbicides applied in the pots were the same as in the fields.The results showed that the herbicides (acetochlor,butachlor,glyphosate-isopropylammonium,aventis,dicamba,and fluroxypyr) had significant impacts on biomass of the maize,infection rate of AM mycorrhiza fungus,and hyphal enzyme activity of alkaline phosphatase (ALP) and succinate dehydrogenase (SDH),and amount of AM mycorrhiza fungal hypha in the soil.Samples collected at the 10th week showed that aventis had greatest impact on biomass of the maize (21.1~31.3 g),and glyphosate isopropylammoniun had the least (59.7~65.5g),while the biomass in the control was 85.4~95.7 g.In terms of impact on infection rate,Butachlor ranks first among the six,resulting in an infection rate of 13.7%~18.1% and Fluroxypyr the last (30.4%~36.6%),while the infection rates in the control were 63.0%~88.2%.Butachlor remained to be the first in terms of impact on ALP and SDH activities of AM mycorrhiza fungal hypha (ALP 8.1%~10.4% and SDH 10.6%~14.6%),and Fluroxypyr the last (ALP 17.0%~20.6% and SDH 23.1%~28.2%),whereas the control showed 38.0%~50.3% and 49.7%~72.4%,respectively;Besides,herbicides also affected significantly total amount of the hyphae of AM mycorrhiza fungus in the soil.