Abstract: By spraying 50 to 200 mg/L La(NO3)3 solutions on leaves of Interspecific hybrid Liriodendron(Liriodendron chinense Sarg.×L.tulipfera L.) seedlings,the effects of rare earth elements(50～200 mg/L La(NO3)3) on growth and phyciological indications in them were studied.The results showed that the seedlings height and diameter at foot were increased greatly,the former from 10 to 19 cm and the later from 1.07 to 2.99 mm per year than that of the control.The content of soluble protein and chlorophyll in leaves were increased by from 40% to 88% in 16～24 days and from 9% to 21% at the eighth day.The ratio of chlorophyll a and b was also increased with the length of treatment days.Besides,rare earth elements reduced the peroxidase (POD) activity especially with 200 mg/L La(NO3)3 decreased by 42.5% at the sixteenth day.This could restrain the activity of IAA oxidase in seedlings and conserve IAA content in order to promote plant growth.The 200 mg/L La(NO3)3 solution was the most effective in three treatment concentrations.