[Objective] To explore the allelopathic effects of volatiles of Eucalyptus grandis × E. urophylla’s leaves on its surrounding crops.[Methods]Seeds of corn,chili and tomato were dealt with fresh leaves of varied qualities taken from Eucalyptus grandis × E. urophylla and eucalyptus oil extracted from fresh leaves,and then seed germination and seedling growth of the three kinds of plants were observed. [Results]Among chili,tomato and corn,volatiles of eucalyptus leaves exerted the least impact on germination of corn seeds and the greatest influence on chili. When leaves used weighed less than 200 g,volatiles of eucalyptus leaves had no obvious effect on seed germination of the three kinds of plants. When leaves used reached 400 g,volatiles could completely inhibit seed germination of chili and tomato,and significantly reduced seed germination of corn( P < 0. 01). With the increase of leaves used,growth of corn seedling were first promoted and then inhibited,both promotion and inhibition on seedling height,fresh weight,dry weight being significant( P < 0. 05) or extremely significant( P < 0. 01). When leaves used weighed less than or just 100 g,volatiles of eucalyptus leaves had no obvious effects on growth of chili and tomato seedlings,yet the volatiles could extremely significantly inhibit the growth of chili and tomato seedlings when leaves used reached 200 g. [Conclusion]Eucalyptus oil’s inhibitory effect on the three tested plants was similar to that of the leaves’ natural volatiles,the effect even being more prominent. [Objective] To explore the allelopathic effects of volatiles of Eucalyptus grandis × E. urophylla’s leaves on its surrounding crops. [Methods] Seeds of corn, chili and tomato were dealt with fresh leaves of varied qualities taken from Eucalyptus grandis × E. urophylla and eucalyptus oil extracted from fresh leaves, and then seed germination and seedling growth of the three kinds of plants were observed. [Results] Among chili, tomato and corn, volatiles of eucalyptus leaves exerted the least impact on germination of corn seeds and the greatest influence when leaves used weighed less than 200 g, volatiles of eucalyptus leaves had no obvious effect on seed germination of the three kinds of plants. When leaves used weighed less than 200 g, volatiles could completely inhibit seed germination of chili and tomato, and significantly reduced the germination of corn (P <0.01). With the increase of leaves used, growth of corn seedling were first promoted and then inhibited, both promotion and inhibition On leaves were weighed less than or just 100 g, volatiles of eucalyptus leaves had no obvious effects on growth (P <0.05) or extremely significant of chili and tomato seedlings, yet the volatiles could extremely significantly inhibit the growth of chili and tomato seedlings when leaves used reached 200 g. [Conclusion] Eucalyptus oil’s inhibitory effect on the three tested plants was similar to that of the leaves’ natural volatiles, the effect even being more prominent