In plant-plant interactions, VOCs, as “pheromones”, can facilitate defense capability of neighboring plants of the same or different species. Plant VOCs can also inhibit seed germination and seedling growth of other plants in the community through allelopathic effects, so the competitiveness and population growth of the VOC emitters are strengthened. The extract of Artemisia frigida Willd. significantly inhibits the seed germination and seedling growth of pasture plants. The similar effects have also been found to result from VOCs, with the effects being stronger on the root growth than on the shoot growth and stronger from VOCs of damaged plants than from that of undamaged plants of A. frigida. In consideration of the characteristics of the allelopathy of A. frigida to plant growth and development, we collected the VOCs from damaged A. frigida plants using the dynamic headspace air-circulation method, identified the main compounds of VOCs with thermal-desorption cold trap/gas chromatography/mass spectrum (TCT/GC/MS), and investigated their effects on root growth and development of four pasture plants (i.e. Melitotus suaveolens Ledeb., Sorghum sudanense, Elymus dahuricus Turcz., Agropyron cristatum L.). Results showed that damaged A. frigida plants emitted 30 types of VOCs, mainly as terpenoids, alcohols, esters, aldehydes and ketones. The compounds with more than 1% relative content accounted for 97.37% of the total VOCs, in which eucalyptol was the most abundant compound (22.43%). The root growth in M. suaveolens, S. sudanense, E. dahuricus and A. cristatum, and the development of lateral roots in S. sudanense and fibrous roots in A. cristatum were significantly inhibited (P＜0.01) and reduced by 5155%, 55.34%, 37.57%, 48.68%, 93.04% and 25.00%, respectively. The root biomass of the four pasture plants was also significantly inhibited (P＜0.01) and reduced by 6184%, 44.81%, 63.95% and 70.97%, respectively. The structures of root stele in the four pasture plants were influenced by the VOCs emitted from damaged A. frigida plants; the phloem, cambium and xylem in M. suaveolens were not differentiated, and the structures of root stele were disordered; the Casparian strips in S. sudanense, E. dahuricus and A. cristatum were not developed completely; and the structures of root stele in S. sudanense and E. dahuricus were disordered. Therefore, it is evident that the VOCs emitted from damaged A. frigida plants markedly influence the root growth and development of pasture plants. Because the development of Casparian strip was not complete due to the impacts of the VOCs emitted from the damaged A. frigida plants, and the differentiation of phloem, cambium and xylem were inhibited, the development of plant roots, the absorption and transport of water and nutrients were restricted in the pasture plants studied. The change in root structure will consequently limit the growth and development of whole plant. The results provide experimental evidence to assist with elucidating the mechanism of the effect of allelopathic substance to the development of seedling root, and with clarifying the mechanism of grassland degradation.