SummaryTemporal dynamics of soil nematode community structure at the depth of 0 -30 cm was compared under invasive Ambrosia trifida and native Chenopodium serotinum in an abandoned cropland in Northeast China. The results showed the difference of nematode taxa and dominant genera under A. trifida and C. serotinum during the study period. Acrobeloides and Paratylenchus were found to be dominant genera under both A. trifida and C. serotinum. Helicotylenchus prevailed in soil with C. serotinum, while Macroposthonia was dominant in soil with A. trifida. Nematode taxa was higher under A. trifida than under C. serotinum from June to September. Except in the July, significantly higher numbers of plant-parasites were observed under A. trifida than under C. serotinum during the study period (P < 0.05). Nematode taxa, Simpson index and structure index were found to be sensitive indicators that detected nematode community structural differences under A. trifida and C. serotinum during the study period.