<p>The effect of external field on the oxidative degradation of AFB1 by plasma activated water was at the M06-2X/aug-cc-pVTZ//M06-2X/6-31G(<i>d</i>) level. For both ·OH addition and ozonolysis of vinyl bond of the terminal furan ring, bimolecular rate coefficients increase with increasing of external field. An increase in the external field leads to an increase in solvent viscosity and, consequently, a decrease in the diffusion rate coefficients. These two opposing effects ultimately result in a decrease in the apparent rate coefficients for ·OH addition and an increase for ozonolysis under the external field. The activation energy for ·OH addition process decreases from 17.02 to 12.17 in the presence of an external field 0.0004 a.u., while the pre-exponential factor decreases by about 12 times. In the ozonolysis process, the activation energy decreases from 10.37 to 10.31, and the pre-exponential factor increases by about 1.26 times. For the degradation of AFB1 by ·OH and ozone in the presence of an external field of 0.0004 a.u., the temperature dependence of the apparent rate coefficients within the range 298.15–320&#xa0;K is given by ln<i>k</i> = (–1463.8/<i>T</i>) + 27.063 and ln<i>k</i> = (–1240.8/<i>T</i>) + 14.208. It can be concluded that AFB1 degradation is highly diffusion-controlled, with the external field exerting a negative impact on the process.</p>