The allelochemicals from aqueous extracts of A. artemisiifolia var. elatior leaves and roots were analyzed and 60 compounds in the leaf and 53 compounds in the roots were inspected. The main compounds were acids,. especially phenolic acids and some non-acids. The total amount of compounds in the aqueous extracts of A. artemisiifolia var. elatior leaves was higher than in the roots. The aqueous extracts had much high inhibiting effects on the germination and seedling elongation of selected plants. In both cases, the inhibiting effects were very different with different selected plants and increased significantly as the concentration of aqueous extracts increased. Capsicum annum, Achyranthes japonica, and Oenothera odorta plants were suffered more significant inhibition effects than Raphnus sativus, Cucumis sativus, Brassica camperstris plants. Aqueous extracts from leaves had slightly higher inhibition effects than the aqueous extracts from the roots.