Abstract: Patulin (PAT) residual is one of the main quality problems of fruit juice industry. In the present work, optical emission spectrometry and high-performance liquid chromatography were used to determine the degradation effect of dielectric barrier discharge (DBD) plasma on PAT. Multiscale oxidation system was constructed to explore the degradation mechanism of PAT. The results were as follows:(1) The DBD plasma produced a large amount of reactive oxygen species (ROS) and reactive nitrogen species (RNS). After 3 min treatment, the pH value of the solution decreased from 4.11±0.01 to 1.96±0.06 (P< 0.05). PAT solution at 500 μg/L was treated with DBD plasma (working voltage:50 kV,working current:1.5 A) for 3 min. The degradation rate of PAT solution was up to(90.92±1.98)% (P< 0.05).(2) Different scavengers were used to screen the active substance to study the effect of active substance on PAT degradation. The degradation rate of PAT after 2 min of DBD plasma treatment was used as an index to evaluate the effect of multiscale oxidation system on the degradation rate of PAT. The degradation rate of PAT decreased from (71.51±1.91)% to (45.77±0.61)% by manganese dioxide, which is a scavenger of hydrogen peroxide (H₂O₂). The degradation rate of PAT decreased to (41.84±1.32)% by tertiary butanol, which is a scavenger of hydroxyl radical (·OH). The degradation rate of PAT decreased to (37.82±0.94)% by para benzoquinone, which is a scavenger of superoxide radical (O₂^-). The degradation rate of PAT decreased to (26.74±1.27)% by sodium dihydrogen phosphate, which is a scavenger of hydrated electron (e_(aq)^-)(P<0. 05). The effect of the four free radicals was in this order:e^-_(aq) >O ₂^- >·OH >H₂O₂. Short-lived species were more effective than long-lived species. The possible mechanism of DBD plasma degradation of PAT was speculated based on above conclusions. DBD plasma produced a large number of complexes, among which short-lived species attacked the lactone ring and unsaturated double bonds of PAT. Eventually, PAT was degraded to carbon dioxide and water.(3)PAT inhibited the growth of E.coli O157∶ H7, while the effect of PAT degradation products on E. coli O157∶ H7 was small. In addition, pH value and active species also affected the growth of E. coli. In conclusion, DBD plasma could effectively degrade PAT in water. The short-lived species produced by plasma played an important role in the degradation process. There was no obvious toxic effect on E. coli by PAT.