Abstract: It is usually difficult to determine disturbance mechanism during distillation processes due to large number of disturbing factors, which makes it hard to improve the accuracy of fault diagnosis.In this paper, disturbance in distillation processes was studied.With reflux flow (L), vapor flow (V), feed composition (z_F) and feed flow (F) as examples, an inversion method was used to establish an inversion model between the disturbance and Euclidean distances based on single variable perturbation.The disturbance could then be analyzed by mathematic calculation.This method was used as an operation rule and embedded into expert systems.The efficacy of the proposed strategy was demonstrated by a high-purity binary distillation column system.