Abstract: Saccharomyces cerevisiae KD was used to ferment mixed juice of apple, kiwi and pear. The removal of patulin by S. cerevisiae during the fermentation of the mixed juice and the toxicity of the degradation product to Escherichia coli were studied. The antioxidant capacity of the juice and its inhibitory effect on α-amylase and lipase were also analyzed during fermentation. The results showed that patulin was degraded completely by S. cerevisiae during mixed juice fermentation, and the degradation product of patulin was not toxic to E. coli. Compared with fresh juice, DPPH·, ABTS⁺·scavenging rate and reducing power were increased by 15.0%, 45.9% and 9.6%, respectively. Besides, the activity of α-amylase and lipase was inhibited by 52.4% and 45.2% with the treatment of the mixed fermented juice. The results would provide scientific basis and technical support for developing functional fermented juice.