With Magnolia denudata Desr.mature seeds as material,we analyzed the volatile components type and content of the sarcotesta by steam distillation and gas chromatography-mass spectrometry.To discussion the ecology and biology function,we has carried comparative study of sarcotesta effect on seed water absorption and loss and the influence on seed germination.The results show that:(1)the sarcotesta accounted for 48.25% of the whole complete seed weight.With/without sarcotesta of M.denudata on the seed water absorption and loss was observed show that the presence of sarcotesta has no significant impact on seed water absorption,but can decrease the water loss rate,indicating it has certain water conservation function.(2)The main types of volatile constituents are terpenes (12) and alcohols (11),but the highest relative content of the components is ketones (32.84%) and the second is esters (18.03%),which include methyl heptenone (31.95%),butyl acetate (17.69%),p-cymene (13.64%) and linalool (6.61%).(3)By investigating the influence of sarcotesta leaching solution on peas and cabbage seed germination,it can be confirmed that the sarcotesta of M.denudata has obvious inhibitory effect.With the increase of concentration of leaching solution,pea seed germination rate reduced from 86.7% to 6.0% and cabbage seed germination rate from 28.0% to zero.We speculate that the sarcotesta of M.denudata in function is a kind of similar structure to pulp of fleshy fruit,which has the rich chemical compositions and plays an important role in its seed dispersal.It not only can attract birds spread their seeds,also has certain allelopathy.