The experiments were undertaken to investigate the dynamics of $NO_3;^-$ uptake at low temperature with forage rape(Bmssica napus), barle(Hordeum vulgare) and winter rye (Scale cereale). A net $NO_3;^-$uptake and the contents of nitrogenous compound in tissues at low temperature ($5^{circ}C$) were compared with normal temperature ($25^{circ}C$).The net uptake of $NO_3;^-$ by Brass ica nqus was the highest among three species at both temperature applied. During 9 hours after temperature treatment, $NO_3;^-$ uptake of Brassica napus, Hordeum vulgm and Scale c e d e grown at $5^{circ}C$ decreased to about 31, 50 and 27% compared with those grown at $25^{circ}C$. $NO_3;^-$ contents in roots were much sensitively affected by low temperature than those of leaves. Comparing with the plants grown at $25^{circ}C$, $NO_3;^-$ contents in roots of increased to 48.3, 38.7 and 53.5% repectively, for Brassica napus, Hordeum vulgare and Scale cereale during 9 days. A relatively less changes in the content of $NH_4;^+$-N were observed according to the temperature treatment. The ontents of amino acids-N in leaves at $5^{circ}C$ slightly decreased while that of roods remarkably increased compared with $25^{circ}C$. Protein-N was the largest pool of nitrogen and its contents in leaves and roots showed a similar response on the temperature treatment. These results suggested that $NO_3;^-$uptake was inhibited at low temperature. The dynamics of $NO_3;^-$ uptake could be closely related to the increased concentration of $NO_3;^-$ and amino acids in roots.