Abstract: A fungi which is able to degrade cinnamic acid efficiently was isolated from cucumber rhizosphere soil by using enrichment and dilution separation methods. This strain could use cinnamic acid as the sole carbon source and was identified as Aspergillus niger by the morphological，biochemical characteristics and molecule analysis. Seed germination treated with degradation liquid of different time indicated that，this fungi could efficiently degrade cinnamic acid and alleviate the inhibition of cinnamic acid on cucumber germination. Seed germination rate，germination index and vigor index could separately reach 100%，92.06% and 91.49% compared with the controls in treatment with degradation liquid of 72 h. Radicle length，radicle area and root tip number also reached 84.19%，87.55% and 82.64%，hypocotyl length and fresh weight is not significant compared with the control.

Key words: cucumber, cinnamic acid, degradation, Aspergillus niger, germination