The simulated process model of the HAc dehydration process under actual overloaded condition was conducted by amending the model of standard condition in our previous work using the process data collected from actual production. Based on the actual process model, the operation optimization analysis of each plant (HAc dehydration column, decanter and NPA recycle column) was conducted using Residue Curve Maps (RCMs), sensitivity analysis and software optimization module. Based on the optimized parameters, the influence of feed impurity MA and the temperature of decanter on the separating effect and energy consumption of the whole process were analyzed. Then the whole process operation optimizing strategy was proposed with the objective that the total reboiler duty Q(Total) of C-1 and C-3 reaches the minimum value, keeping C-1 and C-3 at their optimized separation parameters obtained above, connecting all the broken recycle and connection streams, and using the temperature of D-1 as operation variable. The optimization result shows that the total reboiler duty QTotal of the whole process can reach the minimum value of 128.32 x 10(6) kJ.h(-1) when the temperature of decanter is 352.35 K, and it can save 5.94 x 106 kJ.h(-1), about 2.56 t.h(-1) low-pressure saturated vapor. (c) 2017 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.